An expansion of microorganisms relevant to food and water threats should be considered. Computerized networks should be established to track infectious disease outbreaks in real time. These systems could alert public health and agricultural officials to the existence of a potential bioattack earlier than simply waiting for a report of a suspicious cluster of similar patients. Once a biocrime is suspected, a wide variety of methods are available to identify the microorganism used in the bioattack and to analyze features that might lead to the source of the event.
A multi-pronged approach to such an investigation may be preferable, using many available methods-ranging from genomics to sequencing to physiology to analysis of substances in the sample. Microbial forensics will be most effective if there is sufficient basic scientific information concerning microbial genetics, evolution, physiology, and ecology. Strain subtyping analysis will be difficult to interpret if we do not understand some of the basic evolutionary mechanisms and population diversity of pathogens. Phenotypic features associated with evidentiary pathogens also may provide investigative leads, but full exploitation of these features.
Science can be part of an effective investigative response to a bioterrorism event or a biocrime by providing capabilities to analyze biological and associated signatures in collected evidence. Microbial forensics , a discipline comprised of several scientific fields, is dedicated to the analysis of evidence from such criminal acts to help determine the responsible party and to exonerate the innocent. A partnership has been formed amount a number of government agencies, academia, and the private sector to better respond and deter potential perpetrators of bioterrorism or biocrimes.
The NBFAC, in partnership with the FBI, 1 provides a state-of-the-art central laboratory for the analysis of microbial forensic evidence; and 2 serves as a nexus for integrating the national resources to increase the effectiveness of law enforcement in obtaining the highest level of attribution possible in criminal cases where the weapon is a biological agent.
Resolution in forensic microbial genotyping. Resolution is a key parameter for differentiating among the large number of strain typing methods that could be applied to pathogens involved in bioterror events or biocrimes. In this report we develop a first-principles analysis of strain typing resolution using a simple mathematical model to provide a basis for the rational design of microbial typing systems for forensic applications. We derive two figures of merit that describe the resolving power and phylogenetic depth of a strain typing system.
We also discuss the general problem of how to construct a ''universal'' practical typing system that has the highest possible resolution short of whole-genome sequencing, and that is applicable with minimal modification to a wide range of pathogens. Microbial effects on the development of forensically important blow fly species. Colonisation times and development rates of specific blow fly species are used to estimate the minimum Post Mortem Interval mPMI. The presence or absence of bacteria on a corpse can potentially affect the development and survival of blow fly larvae. Therefore an understanding of microbial -insect interactions is important for improving the interpretation of mPMI estimations.
In this study, the effect of two bacteria Escherichia coli and Staphylococcus aureus on the growth rate and survival of three forensically important blow fly species Lucilia sericata, Calliphora vicina and Calliphora vomitoria was investigated. Sterile larvae were raised in a controlled environment Daily measurements length, width and weight were taken from first instar larvae through to the emergence of adult flies.
Survival rates were also determined at pupation and adult emergence. Results indicate that bacteria were not essential for the development of any of the blow fly species. However, larval growth rates were affected by bacterial diet, with effects differing between blow fly species. Peak larval weights also varied according to species-diet combination; C. These results indicate the potential for the bacteria that larvae are exposed to during development on a corpse to alter both developmental rates and larval weight in some blow fly species.
Chemical and Physical Signatures for Microbial Forensics. Humana Press Chapter 1. Review of history and statement of need. Randy Murch, Virginia Tech Chapter 2. Structure, morphology, and physiology of the microbe as they relate to potential signatures of growth conditions. Special considerations for the forensic arena - quality control, sample integrity, etc. Mark Wilson retired FBI: Western Carolina University Chapter 4.
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Light and electron microscopy, atomic force microscopy, gravimetry etc. Data Reduction and Integrated Microbial Forensics: Validation of high throughput sequencing and microbial forensics applications. High throughput sequencing HTS generates large amounts of high quality sequence data for microbial genomics. The value of HTS for microbial forensics is the speed at which evidence can be collected and the power to characterize microbial -related evidence to solve biocrimes and bioterrorist events. As HTS technologies continue to improve, they provide increasingly powerful sets of tools to support the entire field of microbial forensics.
Interpretation of the results of microbial forensic analyses relies on understanding the performance and limitations of HTS methods, including analytical processes, assays and data interpretation. The utility of HTS must be defined carefully within established operating conditions and tolerances. Validation is essential in the development and implementation of microbial forensics methods used for formulating investigative leads attribution. Three initial aspects of HTS, irrespective of chemistry, instrumentation or software are: Criteria that should be considered for HTS validation for microbial forensics are presented here.
Validation should be defined in terms of specific application and the criteria described here comprise a foundation for investigators to establish, validate and implement HTS as a tool in microbial forensics , enhancing public safety and national security.
Thus, it could not replace detailed empirical measurement of microbial flux at key catchment outlets to underpin faecal indicator source apportionment. Therefore, the MST techniques reported herein currently may not meet the standards required to be a useful forensic tool, although continued development of the methods and further catchment scale studies could increase confidence in such methods for future application. Effective microbial forensic analysis of materials used in a potential biological attack requires robust methods of morphological and genetic characterization of the attack materials in order to enable the attribution of the materials to potential sources and to exclude other potential sources.
The genetic homogeneity and potential intersample variability of many of the category A to C bioterrorism agents offer a particular challenge to the generation of attributive signatures, potentially requiring whole-genome or proteomic approaches to be utilized. Currently, irradiation of mail is standard practice at several government facilities judged to be at particularly high risk. Thus, initial forensic signatures would need to be recovered from inactivated nonviable material.
In the study described in this report, we determined the effects of high-dose gamma irradiation on forensic markers of bacterial biothreat agent surrogate organisms with a particular emphasis on the suitability of genomic DNA gDNA recovered from such sources as a template for whole-genome analysis.
While irradiation of spores and vegetative cells affected the retention of Gram and spore stains and sheared gDNA into small fragments, we found that irradiated material could be utilized to generate accurate whole-genome sequence data on the Illumina and Roche sequencing platforms. The past decade has seen increased development and subsequent adoption of rapid molecular techniques involving DNA analysis for detection of pathogenic microorganisms, also termed microbial forensics.
The continued accumulation of microbial sequence information in genomic databases now better positions the field of high-throughput DNA analysis to proceed in a more manageable fashion. The potential to build off of these databases exists as technology continues to develop, which will enable more rapid, cost effective analyses. This wealth of genetic information, along with new technologies, has the potential to better address some of the current problems and solve the key issues involved in DNA analysis of pathogenic microorganisms.
To this end, a high density fiber optic microarray has been employed, housing numerous DNA sequences simultaneously for detection of various pathogenic microorganisms, including Bacillus anthracis, among others. Each organism is analyzed with multiple sequences and can be sub-typed against other closely related organisms.
For public health labs, real-time PCR methods have been developed as an initial preliminary screen, but culture and growth are still considered the gold standard. Technologies employing higher throughput than these standard methods are better suited to capitalize on the limitless potential garnered from the sequence information. Microarray analyses are one such format positioned to exploit this potential, and our array platform is reusable, allowing repetitive tests on a single array, providing an increase in throughput and decrease in cost, along with a certainty of detection, down to the individual strain level.
Genetics and attribution issues that confront the microbial forensics field. The commission of an act of bioterrorism or biocrime is a real concern for law enforcement and society. Efforts are underway to develop a strong microbial forensic program to assist in identifying perpetrators of acts of bioterrorism and biocrimes, as well as serve as a deterrent for those who might commit such illicit acts. Genetic analyses of microbial organisms will likely be a powerful tool for attribution of criminal acts. There are some similarities to forensic human DNA analysis practices, such as: Evaluation of the Universal Viral Transport system for long-term storage of virus specimens for microbial forensics.
Forensic microbial specimens, including bacteria and viruses, are collected at biocrime and bioterrorism scenes. Although it is preferable that the pathogens in these samples are alive and kept in a steady state, the samples may be stored for prolonged periods before analysis. Therefore, it is important to understand the effects of storage conditions on the pathogens contained within such samples.
To evaluate the capacity to preserve viable virus and the viral genome, influenza virus was added to the transport medium of the Universal Viral Transport system and stored for over 3 months at various temperatures, after which virus titrations and quantitative analysis of the influenza hemagglutinin gene were performed. This study provides important information for the handling of forensic virus specimens.
The need for high-quality whole-genome sequence databases in microbial forensics. Microbial forensics is an important part of a strengthened capability to respond to biocrime and bioterrorism incidents to aid in the complex task of distinguishing between natural outbreaks and deliberate acts. The goal of a microbial forensic investigation is to identify and criminally prosecute those responsible for a biological attack, and it involves a detailed analysis of the weapon--that is, the pathogen.
The recent development of next-generation sequencing NGS technologies has greatly increased the resolution that can be achieved in microbial forensic analyses. It is now possible to identify, quickly and in an unbiased manner, previously undetectable genome differences between closely related isolates. This development is particularly relevant for the most deadly bacterial diseases that are caused by bacterial lineages with extremely low levels of genetic diversity. Whole-genome analysis of pathogens is envisaged to be increasingly essential for this purpose.
In a microbial forensic context, whole-genome sequence analysis is the ultimate method for strain comparisons as it is informative during identification, characterization, and attribution--all 3 major stages of the investigation--and at all levels of microbial strain identity resolution ie, it resolves the full spectrum from family to isolate. Given these capabilities, one bottleneck in microbial forensics investigations is the availability of high-quality reference databases of bacterial whole-genome sequences. To be of high quality, databases need to be curated and accurate in terms of sequences, metadata, and genetic diversity coverage.
The development of whole-genome sequence databases will be instrumental in successfully tracing pathogens in the future. Forensic biology is a sub-discipline of biological science with an amalgam of other branches of science used in the criminal justice system. These biological materials of human origin are rich source of proteins, carbohydrates, lipids, trace elements as well as water and, thus, provide a virtuous milieu for the growth of microbes.
The obstinate microbial growth augments the degradation process and is amplified with the passage of time and improper storage of the biological materials. Degradation of these biological materials carriages a huge challenge in the downstream processes of forensic DNA typing technique, such as short tandem repeats STR DNA typing.
Microbial degradation yields improper or no PCR amplification, heterozygous peak imbalance, DNA contamination from non-human sources, degradation of DNA by microbial by-products, etc. Consequently, the most precise STR DNA typing technique is nullified and definite opinion can be hardly given with degraded forensic exhibits.
Thus, suitable precautionary measures should be taken for proper storage and processing of the biological exhibits to minimize their decaying process by micro-organisms. Current regulations in the United States stipulate that the microbial quality of waters used for consumption and recreational activities should be determined regularly by measuring microbial indicators of fecal pollution. Hence, the microbial risk associated with these waters is A study focused on the effects of forensic participation on two specific traits--argumentativeness and verbal aggression.
Two hundred eighty-one high school forensic students participating at a large western forensic tournament in the beginning of the academic year completed D. Infante's Argumentative and Verbal Aggression Scales. Budowle, Bruce; Beaudry, Jodi A. The risk and threat of bioterrorism and biocrime have become a large concern and challenge for governments and society to enhance biosecurity. Law enforcement plays an important role in assessing and investigating activities involved in an event of bioterrorism or biocrime.
Key to a successful biosecurity program is increased awareness and early detection of threats facilitated by an integrated network of responsibilities and capabilities from government, academic, private, and public assets. To support an investigation, microbial forensic sciences are employed to analyze and characterize forensic evidence with the goal of attribution or crime scene reconstruction. Two different molecular biology-based assays — real time polymerase chain reaction PCR and repetitive element PCR — are described and demonstrate how molecular biology tools may be utilized to aid in the investigative process.
Technologies relied on by microbial forensic scientists need to be properly validated so that the methods used are understood and so that interpretation of results is carried out within the limitations of the assays. The three types of validation are preliminary, developmental, and internal. The first is necessary for rapid response when a threat is imminent or an attack has recently occurred.
The latter two apply to implementation of routinely used procedures. The development of paleomicrobiology with new molecular techniques such as metagenomics is revolutionizing our knowledge of microbial evolution in human history. The study of microbial agents that are concomitantly active in the same biological environment makes it possible to obtain a picture of the complex interrelations among the different pathogens and gives us the perspective to understand the microecosystem of ancient times.
This research acts as a bridge between disciplines such as archaeology, biology, and medicine, and the development of paleomicrobiology forces archaeology to broaden and update its methods. This chapter addresses the archaeological issues related to the identification of cemeteries from epidemic catastrophes typology of burials, stratigraphy, topography, paleodemography and the issues related to the sampling of human remains for biomolecular analysis. Developments in the field of paleomicrobiology are described with the example of the plague.
Because of its powerful interdisciplinary features, the paleomicrobiological study of Yersinia pestis is an extremely interesting field, in which paleomicrobiology, historical research, and archeology are closely related, and it has important implications for the current dynamics of epidemiology. Exploitation of microbial forensics and nanotechnology for the monitoring of emerging pathogens. Emerging infectious diseases remain among the leading causes of global mortality.
Traditional laboratory diagnostic approaches designed to detect and track infectious disease agents provide a framework for surveillance of bio threats. However, surveillance and outbreak investigations using such time-consuming approaches for early detection of pathogens remain the major pitfall.
SAMPLE COLLECTION
Hence, reasonable real-time surveillance systems to anticipate threats to public health and environment are critical for identifying specific aetiologies and preventing the global spread of infectious disease. The current review discusses the growing need for monitoring and surveillance of pathogens with the same zeal and approach as adopted by microbial forensics laboratories, and further strengthening it by integrating with the innovative nanotechnology for rapid detection of microbial pathogens.
Such innovative diagnostics platforms will help to track pathogens from high risk areas and environment by pre-emptive approach that will minimize damages. The various scenarios with the examples are discussed where the high risk associated human pathogens in particular were successfully detected using various nanotechnology approaches with potential future prospects in the field of microbial forensics.
Microbial soil community analyses for forensic science: Application to a blind test. Soil complexity, heterogeneity and transferability make it valuable in forensic investigations to help obtain clues as to the origin of an unknown sample, or to compare samples from a suspect or object with samples collected at a crime scene. In a few countries, soil analysis is used in matters from site verification to estimates of time after death.
However, up to date the application or use of soil information in criminal investigations has been limited. In particular, comparing bacterial communities in soil samples could be a useful tool for forensic science. To evaluate the relevance of this approach, a blind test was performed to determine the origin of two questioned samples one from the mock crime scene and the other from a Both techniques discriminated well between soils from a single source, but a combination of both techniques was necessary to show that the origin was a mixture of soils.
This study illustrates the potential of applying microbial ecology methodologies in soil as an evaluative forensic tool. Drywall manufactured in China released foul odors attributed to volatile sulfur compounds. These included hydrogen sulfide, methyl mercaptan, and sulfur dioxide. Given that calcium sulfate is the main component of drywall, one would suspect bacterial reduction of sulfate to sulfide as the primary culprit.
However, when the forensics , i. Forensic evidence suggests that the transformation of elemental sulfur went through several abiological and microbial stages: Microbial DNA fingerprinting of human fingerprints: We tested the suitability of physical fingerprints for revealing human host information, with geographic inference as example, via microbial DNA fingerprinting.
We showed that the transient exogenous fingertip microflora is frequently different from the resident endogenous bacteria of the same individuals. While microbial species differed considerably in their frequency spectrum between fingerprint samples from volunteers in Europe and southern Asia, there was no clear geographic distinction between Staphylococcus strains in a cluster analysis, although bacterial genotypes did not overlap between both continental regions. Our results, though limited in quantity, clearly demonstrate that the dynamic fingerprint microflora challenges human host inferences for forensic purposes including geographic ones.
Overall, our results suggest that human fingerprint microflora is too dynamic to allow for forensic marker developments for retrieving human information. Electronic supplementary material The online version of this article doi: Cost- effective forensic image enhancement. The forensic value of this examination in a major homicide investigation was apparent to the viewer. Equally clear was the potential for extracting evidence which is beyond the reach of conventional detection techniques. The cost of this technology in , however, was prohibitive, and well beyond the means of most police agencies.
Twenty-two years later, a highly efficient means of image enhancement is easily within the grasp of most police agencies, not only for homicides but for any case application. A PC workstation combined with an enhancement software package allows a forensic investigator to fully exploit digital technology. The goal of this approach is the optimization of the signal to noise ratio in images.
Obstructive backgrounds may be diminished or eliminated while weak signals are optimized by the use of algorithms including Fast Fourier Transform, Histogram Equalization and Image Subtraction. An added benefit is the speed with which these processes are completed and the results known. The efficacy of forensic image enhancement is illustrated through case applications.
We examined effects of participation and forensic context on 4-year-old children's testimony. Children in "participant" and "police" conditions actively participated in games with a "babysitter"; each child in the "observer" condition watched a videotape of a child and the babysitter playing. Eleven days later, children were individually questioned about the event.
Before the interview began, children in the police condition talked to a police officer who said the babysitter might have done something bad. Comparison of participant- and observer-condition performance indicated that participation increased free-recall accuracy concerning actions that took place and lowered suggestibility.
Comparison of participant- and police-condition performance indicated that forensic context led to increased error in free recall and additional comments to misleading questions. However, forensic context also resulted in higher accuracy on an age-identification task and did not affect children's accuracy in answering abuse-related questions. Large-scale genomics projects are identifying biomarkers to detect human disease.
Accurate characterization of metagenomic samples is dependent on accurate measurements of genetic variation between isolates with resolution down to strain level. Often single biomarker sensitivity is augmented by use of multiple or panels of biomarkers. In parallel with single biomarker validation, advances in DNA sequencing enable analysis of entire genomes in a single run: Potentially, direct sequencing could be used to analyze an entire genome to serve as the biomarker for genome identification.
However, genome variation and population diversity complicate use of direct sequencing, as well as differences caused by sample preparation protocols including sequencing artifacts and mistakes. As part of a Department of Homeland Security program in bacterial forensics , we examined how to implement whole genome sequencing WGS analysis as a judicially defensible forensic method for attributing microbial sample relatedness; and also to determine the strengths and limitations of whole genome sequence analysis in a forensics context.
Herein, we demonstrate use of sequencing to provide genetic characterization of populations: The nascent field of microbial forensics requires the development of diverse signatures as indicators of various aspects of the production environment of microorganisms. We have characterized isotopic relationships between Bacillus subtilis ATCC spores and their growth environment, using as a database the carbon, nitrogen, oxygen and hydrogen stable isotope ratios of a total of separate cultures of spores produced on a total of 32 different culture media.
We have analyzed variation within individual samples, between cultures produced in tandem, and between cultures produced in the same medium but at different times in the context of using stable isotope ratios as a signature for sample matching. We have correlated the stable isotope ratios of carbon, nitrogen, oxygen, and hydrogen of growth medium nutrients or water and spores and show examples of how these relationships can be used to exclude nutrient or water samples as possible growth substrates for specific cultures.
The power of stable isotope ratio data can be greatly enhanced by combining it with orthogonal datasets that speak to different aspects of an organism's production environment. We developed a Bayesian network that follows the causal relationship from culture medium recipe to spore elemental content as measured by secondary ion mass spectrometry SIMS , carbon and nitrogen stable isotope ratios, and to the presence of residual agar by electrospray ionization MS ESI-MS.
The network was developed and tested on data from three replicate cultures of B. This network was able to characterize. Vaginal microbial flora analysis by next generation sequencing and microarrays; can microbes indicate vaginal origin in a forensic context? Forensic analysis of biological traces generally encompasses the investigation of both the person who contributed to the trace and the body site s from which the trace originates.
For instance, for sexual assault cases, it can be beneficial to distinguish vaginal samples from skin or saliva samples. In this study, we explored the use of microbial flora to indicate vaginal origin. Next, we selected candidate probes targeting genera or species and designed a microarray, with which we analysed a diverse set of samples; 43 DNA extracts from vaginal samples and 25 DNA extracts from samples from other body sites, including sites in close proximity of or in contact with the vagina.
Finally, we used the microarray results and next generation sequencing dataset to assess the potential for a future approach that uses microbial markers to indicate vaginal origin. Microarray analysis of a sample will then render a microbial flora pattern that is probably best analysed in a probabilistic approach. Evolving from discriminating distinct microbes to characterizing entire microbial communities on decomposing remains.
The body of an animal encompasses a multitude of compositionally and functionally unique microbial environments, from the skin to the gastrointestinal system. Each of these systems harbor microbial communities that have adapted in order to cohabitate with their specific host resulting in a distinct Kournikakis Resumen La microbiologia forense es una Entre las importantes razones que motivan una.
Statistical modeling of the evaluation of evidence with the use of the likelihood ratio has a long history. It dates from the Dreyfus case at the end of the nineteenth century through the work at Bletchley Park in the Second World War to the present day. The development received a significant boost in with a seminal work by Dennis Lindley which introduced a Bayesian hierarchical random effects model for the evaluation of evidence with an example of refractive index measurements on fragments of glass.
Many models have been developed since then. The methods have now been sufficiently well-developed and have become so widespread that it is timely to try and provide a software package to assist in their implementation. Software for the Analysis and Implementation of Likelihood Ratios was funded by the European Network of Forensic Science Institutes through their Monopoly programme to develop a software package for use by forensic scientists world-wide that would assist in the statistical analysis and implementation of the approach based on likelihood ratios.
It is the purpose of this document to provide a short review of a small part of this history. Context effects are pervasive in forensic science, and are being recognized by a growing number of disciplines as a threat to objectivity. Cognitive processes can be affected by extraneous context information, and many proactive scientists are therefore introducing context-minimizing systems into their laboratories. Forensic entomologists are also subject to context effects , both in the processes they undertake e. We stratify the risk of bias into low, medium, and high for the decisions and processes undertaken by forensic entomologists, and propose that knowledge of the time the deceased was last seen alive is the most potentially biasing piece of information for forensic entomologists.
Effective use of forensic science in volume crime investigations: New scientific, technological and legal developments, particularly the introduction of national databases for DNA and fingerprints, have led to increased use of forensic science in the investigation of crime.
There is an assumption, and in some instances specific assertions, that such developments bring improvements either in broad criminal justice terms or more narrowly in terms of economic or practical efficiencies. The underlying presumption is that the new technological opportunities will be understood and effectively implemented.
This research investigates whether such increases in activity have also been accompanied by improvements in the effective use of forensic science. A systematic review of thirty-six reports published predominantly in England and Wales since the s, which have considered the use of forensic science in the investigation of volume crimes, was carried out. These reports have identified a number of recurrent themes that influenced how effectively forensic science was used in investigations. The themes identified included forensic knowledge and training of investigators, communication and information exchange between specialists and investigators, timeliness of forensic results, interagency relationships and deployment of crime scene examiner resources.
The research findings suggest that these factors continue to hinder the effective use of forensic science despite technological advances and this paper considers their potential causes. The forensic nursing in sexual assaults: Sexual assault was a ubiquitous and serious problem in our society. The world's care centers and forensic associations, which were at the forefront of scientific research in sexual assaults, discussed the role of the Forensic Nursing in their early diagnosis and their prevention, but little has been written in literature regarding their appropriate management.
This article focuses on the immunochemical laboratory investigation in diagnosis and prevention of its adverse effects in sexual assaults and the role of the Forensic Nursing played in this task. After a careful reading of all the material received from many of the care centers and the associations contacted, a Forensic Nursing Examination Program, with specific immunochemical address, is identified.
Effects of Participation and Forensic Context. This study, with 39 4-year-olds, found that children had better free recall accuracy and lowered suggestibility when they participated with a "babysitter" rather than observed a babysitter and child. Addition of forensic context by a policeman prior to questioning increased error in free recall but did not affect children's accuracy in…. Illustration and analysis of a coordinated approach to an effective forensic trace evidence capability. An effective trace evidence capability is defined as one that exploits all useful particle types, chooses appropriate technologies to do so, and directly integrates the findings with case-specific problems.
Limitations of current approaches inhibit the attainment of an effective capability and it has been strongly argued that a new approach to trace evidence analysis is essential. A hypothetical case example is presented to illustrate and analyze how forensic particle analysis can be used as a powerful practical tool in forensic investigations.
The specifics in this example, including the casework investigation, laboratory analyses, and close professional interactions, provide focal points for subsequent analysis of how this outcome can be achieved. This leads to the specification of five key elements that are deemed necessary and sufficient for effective forensic particle analysis: A coordinating role, absent in current approaches to trace evidence analysis, is essential to achieving these elements. However, the level of expertise required for the coordinating role is readily attainable. Some additional laboratory protocols are also essential.
However, none of these has greater staffing requirements than those routinely met by existing forensic trace evidence practitioners. The major challenges that remain are organizational acceptance, planning and implementation. The challenges and effects of globalisation on forensic dentistry. This paper deals with the challenges faced by forensic dentists in a world in which globalisation has become a reality. Even differences in the background matrix carrying the evidence material may warrant changes in the sampling strategy.
Thus, in some scenarios it might be good practice to collect multiple samples and use several different preservation modalities to accommodate different analytical schemes see recommendations below for a strategy to begin to address the major concerns for sampling. The methods and devices for evidence collection must be validated with regard to subsequent analytical processes. Consider a scenario in which a crime scene investigator uses a swab with a cm diameter to collect evidence over large surface areas. Although validation testing shows that such a swab is effective for collecting microorganisms, most if not all diagnostic and analytical laboratories cannot accommodate such a large swab for sample processing e.
This exaggerated example stresses the point that validation should be designed with consideration of the entire process from collection to analysis. Alternatively, swabs may contain soluble components that may be either cytotoxic for cell culture systems used to recover viruses or inhibitory for the growth of certain bacteria in culture. Some materials designed to preserve a particular pathogen may impact negatively on the analytical assay.
In the clinical laboratory, specimens containing bacteria tend to be delivered in general transport media e. Viral transport media usually consist of solutions such as phosphate-buffered sucrose or Hanks balanced salt solution with bovine serum albumin and some antibiotics to retard bacterial growth. Many commercial PCR or antigen detection kits provide proprietary transport media that have been designed to stabilize the analyte in question. There also are some general transport solutions for collection of samples for PCR analysis that lyse the bacteria or viruses and stabilize the nucleic acids 13 , 18 , The media generally used to collect and transport animal pathogens also were developed primarily to preserve proteins, nucleic acids, and pathogen viability.
The stability of some animal viruses e.
Quality Sample Collection, Handling, and Preservation for an Effective Microbial Forensics Program
One of the most commonly used transport media is buffered tryptose broth. Buffered glycerin, internationally used to transport vesicular disease specimens, has been shown to preserve the causative virus at room temperature for long periods of time. Glycerol, at different concentrations, may inactivate certain viruses while preserving others in clinical samples 25 , 41 , A possible criterion for selecting an adequate collection and transport medium for viruses of agricultural concern could be the use of isotonic solutions with neutral pH Additional guidance for collection of virus specimens can be found at http: The number and intricacies of the areas under consideration emphasize the need for extensive training and knowledge to allow flexibility in the development of sampling strategies that are best suited for each set of circumstances.
Obtaining an analytical result also can be affected by the manner and conditions under which a specimen is transported and stored. The same concerns discussed above with respect to sample collection also apply to packaging and transportation. Storage conditions differ for some microorganisms.
For example, anaerobes die when they are exposed to ambient levels of oxygen during storage and therefore cannot be recovered upon anaerobic culture The packaging or storage conditions required for a given microorganism also may differ depending on the sample matrix or physical condition e. When there are copious quantities of microbial forensic evidence, some loss may be inconsequential, and various packaging and storage strategies can be applied.
However, trace materials are very limited, and at times collection of only one sample may be possible. In such scenarios, efforts to maintain the integrity of the sample are more demanding and critical. The packaging, transportation, and storage conditions should be related to preserving the analyte or signature to be analyzed. Clinical medicine has well-developed packaging, transport, and storage protocols 15 , 16 , 27 , Each specimen is transported in a package appropriate for the suspected microorganism and the type of specimen collected.
Packaging for most routine pathogens and the pathogens on the select agent list 2 is defined, and the likely clinical specimens in which they reside are known Commercial products are available for transporting clinical specimens. Transport packages designed for most bacteria are not adequate if a viral etiology is suspected. Specimens for culture should be transported to the laboratory as promptly as possible.
Transport strategies that minimize damage, loss, contamination, or exposure to personnel are necessary Some specimens can be transported at room temperature, and some should be transported on ice see reference 44 for some recommended conditions. Most specimens should be stored refrigerated to maintain viability, preserve relative proportions, and minimize overgrowth of contaminants blood is an important exception and should not be refrigerated. Many commercial clinical laboratories have developed efficient and effective methods for defining transport media and appropriate temperatures for particular classes of microbes.
Under certain circumstances, the collection of a specimen for microbial forensics is more like the collection of a cerebrospinal fluid sample 14 , 34 or a surgical biopsy from a patient where it may be difficult or impossible to obtain a second sample. Because it may be difficult to predict the optimal transport materials or process, a variety of options should be made available to crime scene investigators, and there should be consultation with experts, when possible, prior to packaging. For food or plant materials, the recommended packaging and storage practices are similar to those used in clinical microbiology and have been well described Sampling and sample plans for foods are discussed in detail elsewhere Such methods depend on the nature of the food e.
To minimize amplification during transport or storage, when possible, the sample should be maintained dry, frozen, or at least chilled. However, some microorganisms may be harmed if they are frozen. Buffered glycerol has been used to minimize injury due to freezing and thawing Methods that do not cause significant decreases in the viabilities of specific organisms improve typing success If an act of bioterrorism were perpetrated against agricultural targets, sampling of crops and environmental materials would be required.
Samples of plant tissues or associated materials, such as insects, nematodes, soil, or water, should be collected directly into a container with minimal contact. In the field, plant tissues are usually placed dry into paper or plastic bags and stored on ice until they can be refrigerated or processed. In some cases, adding a small amount of sterile glycerol to the plastic bag may delay tissue desiccation and preserve pathogen signatures. Plastic sandwich box humidity chambers can maintain humidity without directly wetting plant tissues or insects.
Long-term storage of forensic microbial samples prior to analysis is often necessary; however, long-term storage conditions have not been well defined. Optimal storage conditions freezing versus refrigeration or lyophilization, humidity, storage media and sample longevities have been determined for only a few plant pathogens. While some of the practices described above apply in general to collection of forensic samples, many times samples are collected from the environment surrounding a crime scene. In such cases, the state of the agent should be considered.
For example, cooling of dry material may produce condensation that could alter its physical state and possibly interfere with subsequent analysis. As a general practice, collected samples are placed into sterile containers using dedicated sterile collection tools. The samples are then placed into prelabeled translucent ziplock bags for secondary containment and maintained at ambient temperature. A ziplock bag used as either primary or secondary containment for contaminated physical evidence may be contaminated during sample collection. Therefore, the exterior of sample containers should be decontaminated.
The protocols for packaging and transporting samples to laboratories for analysis are based on federal regulations designed to avoid inadvertent release of infectious substances However, for forensic analyses, maintaining the integrity and authenticity of samples from the point of collection is paramount, and following minimal transport regulations may not be adequate. There is a need to validate transport and storage methods for as many agents and analytes of concern as possible.
In addition, because remaining evidence should be made available to the defense for retesting, if desired, proper long-term storage conditions have to be validated. It is important to draw distinctions between investigations designed to gather microbial forensic evidence and investigations designed to determine whether a pathogen is still present, perhaps after a remediation effort.
A recent GAO report provided recommendations concerned predominantly with remediation. However, some important areas of overlap with evidence collection for law enforcement purposes are instructive. The GAO report 40 addressed and was consistent with many of the issues discussed at the recent conference. The scientists in attendance generally agreed with and supported the findings of the GAO report in that validation of methods and processes was deemed necessary to achieve best practices. However, the conference attendees cautioned that the sampling strategy advocated by the authors of the GAO report for postremediation analysis should not be extrapolated to, nor is it the best approach for, microbial forensic or initial public health and agricultural health investigations.
The GAO report was critical of the targeted sampling strategy used to detect Bacillus anthracis in postal facilities in In this instance, government agencies collected samples where, in their best judgment, B. As noted above, the report apparently pertains to remediation and the decision of when to consider a building safe for reoccupation. Whereas such verification sampling may be necessary to confirm decontamination of a building 10 , it should not be confused with the different requirements of microbial forensics.
In clinical and agricultural diagnoses, sampling is prioritized based on location, the type and extent of symptoms, prior knowledge based on sound principles, and the materials available rather than randomly across the body of an infected individual, a field, or any location.
Likewise, it would not be productive for most forensic or clinical investigations to use a randomized sample collection strategy. For example, if a patient presents with fever, difficulty with breathing, and a productive cough but no headache or stiff neck, a physician would likely obtain a sputum sample to search for a possible microbial etiology rather than randomly gather samples that include a lumbar puncture for cerebrospinal fluid or collect gastrointestinal samples to look for parasites. Similarly, fever, headache, and a stiff neck would direct the physician to consider meningitis as the diagnosis and target sampling to the cerebrospinal fluid to determine if an infection was present.
For investigations involving plants, if necrotic lesions are present, it is best to obtain samples from the lesion edges, where living plant tissue supports active pathogen growth. Certain specialized pathogen structures, such as the galls of smut fungi or the tumors produced by the crown gall bacterium, may be collected directly.
In a food poisoning case, consumption of a food may be epidemiologically associated with illness resulting from contamination with a food-borne pathogen. To identify the microorganism, it would be more effective to collect samples from the individuals who became ill than to collect samples from randomly selected individuals in the population. In one example of a food-borne outbreak that involved a targeted investigation and subsequent reexamination , strawberries were associated initially with development of illness in a number of people. Although the cause was subsequently shown to be Cyclospora cayetanensis , a gastrointestinal agent found in raspberries from Guatemala 20 , targeted sampling was clearly advantageous in collecting the most informative samples.
Similarly, the presence of castor beans or bean mash at a crime scene, or even access to internet records, would suggest the use of directed sampling methods for the collection of suspected ricin. Just as a clinical investigation or a food-borne illness investigation should use the patient history, physical examination, and blood work to direct sampling, a forensic investigation should use available information to guide sampling. In other words, procedures that would have the highest diagnostic yield are given priority.
Certain factors can diminish the likelihood of a positive finding with samples. Using food-borne contamination as an example, these factors include increased time from contamination to sampling, uneven dispersal of the pathogen in the contaminated food, a very large volume of food to be sampled, large batch size, short shelf life of the food, rapid turnaround of implicated foods, and incorrect linkage between the food and illness. These factors suggest that a sampling regimen targeted to only the implicated food s , its most probable source s , or the site s of origin for similar foods is the preferred sampling approach.
Despite the clear utility of targeted sampling in forensic and epidemiologic investigations, statistically derived or random sampling strategies may be useful sometimes. Although statistically derived or random sampling strategies have not been used routinely in the forensic sciences, it may be necessary in some instances to understand sample-to-sample variability when workers try to compare other factors across the environment.
Maintaining a chain of custody on evidentiary samples is one example of an extra requirement imposed on an investigation of a biocrime. Another issue is the intent in microbial forensics to identify a bioattack organism in greatest detail. If possible, forensic investigations will strive to identify the precise strain and substrain, rather than just to the species level, which might be sufficient in an epidemiological investigation.
Although multiple groups have developed lists of bioterrorism target pathogens, these lists are too narrow. An expansion of microorganisms relevant to food and water threats should be considered. Computerized networks should be established to track infectious disease outbreaks in real time. These systems could alert public health and agricultural officials to the existence of a potential bioattack earlier than simply waiting for a report of a suspicious cluster of similar patients.
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Once a biocrime is suspected, a wide variety of methods are available to identify the microorganism used in the bioattack and to analyze features that might lead to the source of the event. A multi-pronged approach to such an investigation may be preferable, using many available methods-ranging from genomics to sequencing to physiology to analysis of substances in the sample. Microbial forensics will be most effective if there is sufficient basic scientific information concerning microbial genetics, evolution, physiology, and ecology.
Strain subtyping analysis will be difficult to interpret if we do not understand some of the basic evolutionary mechanisms and population diversity of pathogens. Phenotypic features associated with evidentiary pathogens also may provide investigative leads, but full exploitation of these features. Science can be part of an effective investigative response to a bioterrorism event or a biocrime by providing capabilities to analyze biological and associated signatures in collected evidence.
Get Chemical and Physical Signatures for Microbial Forensics: PDF
Microbial forensics , a discipline comprised of several scientific fields, is dedicated to the analysis of evidence from such criminal acts to help determine the responsible party and to exonerate the innocent. A partnership has been formed amount a number of government agencies, academia, and the private sector to better respond and deter potential perpetrators of bioterrorism or biocrimes.
The NBFAC, in partnership with the FBI, 1 provides a state-of-the-art central laboratory for the analysis of microbial forensic evidence; and 2 serves as a nexus for integrating the national resources to increase the effectiveness of law enforcement in obtaining the highest level of attribution possible in criminal cases where the weapon is a biological agent.
Resolution in forensic microbial genotyping. Resolution is a key parameter for differentiating among the large number of strain typing methods that could be applied to pathogens involved in bioterror events or biocrimes. In this report we develop a first-principles analysis of strain typing resolution using a simple mathematical model to provide a basis for the rational design of microbial typing systems for forensic applications.
We derive two figures of merit that describe the resolving power and phylogenetic depth of a strain typing system. We also discuss the general problem of how to construct a ''universal'' practical typing system that has the highest possible resolution short of whole-genome sequencing, and that is applicable with minimal modification to a wide range of pathogens. Microbial effects on the development of forensically important blow fly species. Colonisation times and development rates of specific blow fly species are used to estimate the minimum Post Mortem Interval mPMI.
The presence or absence of bacteria on a corpse can potentially affect the development and survival of blow fly larvae. Therefore an understanding of microbial -insect interactions is important for improving the interpretation of mPMI estimations. In this study, the effect of two bacteria Escherichia coli and Staphylococcus aureus on the growth rate and survival of three forensically important blow fly species Lucilia sericata, Calliphora vicina and Calliphora vomitoria was investigated.
Sterile larvae were raised in a controlled environment Daily measurements length, width and weight were taken from first instar larvae through to the emergence of adult flies. Survival rates were also determined at pupation and adult emergence. Results indicate that bacteria were not essential for the development of any of the blow fly species. However, larval growth rates were affected by bacterial diet, with effects differing between blow fly species.
Peak larval weights also varied according to species-diet combination; C.
These results indicate the potential for the bacteria that larvae are exposed to during development on a corpse to alter both developmental rates and larval weight in some blow fly species. Chemical and Physical Signatures for Microbial Forensics.
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Humana Press Chapter 1. Review of history and statement of need. Randy Murch, Virginia Tech Chapter 2. Structure, morphology, and physiology of the microbe as they relate to potential signatures of growth conditions. Special considerations for the forensic arena - quality control, sample integrity, etc. Mark Wilson retired FBI: Western Carolina University Chapter 4. Light and electron microscopy, atomic force microscopy, gravimetry etc. Data Reduction and Integrated Microbial Forensics: Validation of high throughput sequencing and microbial forensics applications.
High throughput sequencing HTS generates large amounts of high quality sequence data for microbial genomics. The value of HTS for microbial forensics is the speed at which evidence can be collected and the power to characterize microbial -related evidence to solve biocrimes and bioterrorist events. As HTS technologies continue to improve, they provide increasingly powerful sets of tools to support the entire field of microbial forensics. Interpretation of the results of microbial forensic analyses relies on understanding the performance and limitations of HTS methods, including analytical processes, assays and data interpretation.
The utility of HTS must be defined carefully within established operating conditions and tolerances. Validation is essential in the development and implementation of microbial forensics methods used for formulating investigative leads attribution. Three initial aspects of HTS, irrespective of chemistry, instrumentation or software are: Criteria that should be considered for HTS validation for microbial forensics are presented here.
Validation should be defined in terms of specific application and the criteria described here comprise a foundation for investigators to establish, validate and implement HTS as a tool in microbial forensics , enhancing public safety and national security. Thus, it could not replace detailed empirical measurement of microbial flux at key catchment outlets to underpin faecal indicator source apportionment. Therefore, the MST techniques reported herein currently may not meet the standards required to be a useful forensic tool, although continued development of the methods and further catchment scale studies could increase confidence in such methods for future application.
Effective microbial forensic analysis of materials used in a potential biological attack requires robust methods of morphological and genetic characterization of the attack materials in order to enable the attribution of the materials to potential sources and to exclude other potential sources. The genetic homogeneity and potential intersample variability of many of the category A to C bioterrorism agents offer a particular challenge to the generation of attributive signatures, potentially requiring whole-genome or proteomic approaches to be utilized.
Currently, irradiation of mail is standard practice at several government facilities judged to be at particularly high risk. Thus, initial forensic signatures would need to be recovered from inactivated nonviable material. In the study described in this report, we determined the effects of high-dose gamma irradiation on forensic markers of bacterial biothreat agent surrogate organisms with a particular emphasis on the suitability of genomic DNA gDNA recovered from such sources as a template for whole-genome analysis.
While irradiation of spores and vegetative cells affected the retention of Gram and spore stains and sheared gDNA into small fragments, we found that irradiated material could be utilized to generate accurate whole-genome sequence data on the Illumina and Roche sequencing platforms. The past decade has seen increased development and subsequent adoption of rapid molecular techniques involving DNA analysis for detection of pathogenic microorganisms, also termed microbial forensics. The continued accumulation of microbial sequence information in genomic databases now better positions the field of high-throughput DNA analysis to proceed in a more manageable fashion.
The potential to build off of these databases exists as technology continues to develop, which will enable more rapid, cost effective analyses. This wealth of genetic information, along with new technologies, has the potential to better address some of the current problems and solve the key issues involved in DNA analysis of pathogenic microorganisms. To this end, a high density fiber optic microarray has been employed, housing numerous DNA sequences simultaneously for detection of various pathogenic microorganisms, including Bacillus anthracis, among others.
Each organism is analyzed with multiple sequences and can be sub-typed against other closely related organisms. For public health labs, real-time PCR methods have been developed as an initial preliminary screen, but culture and growth are still considered the gold standard. Technologies employing higher throughput than these standard methods are better suited to capitalize on the limitless potential garnered from the sequence information.
Microarray analyses are one such format positioned to exploit this potential, and our array platform is reusable, allowing repetitive tests on a single array, providing an increase in throughput and decrease in cost, along with a certainty of detection, down to the individual strain level. Genetics and attribution issues that confront the microbial forensics field.
The commission of an act of bioterrorism or biocrime is a real concern for law enforcement and society. Efforts are underway to develop a strong microbial forensic program to assist in identifying perpetrators of acts of bioterrorism and biocrimes, as well as serve as a deterrent for those who might commit such illicit acts.
Genetic analyses of microbial organisms will likely be a powerful tool for attribution of criminal acts. There are some similarities to forensic human DNA analysis practices, such as: Evaluation of the Universal Viral Transport system for long-term storage of virus specimens for microbial forensics. Forensic microbial specimens, including bacteria and viruses, are collected at biocrime and bioterrorism scenes. Although it is preferable that the pathogens in these samples are alive and kept in a steady state, the samples may be stored for prolonged periods before analysis.
Therefore, it is important to understand the effects of storage conditions on the pathogens contained within such samples. To evaluate the capacity to preserve viable virus and the viral genome, influenza virus was added to the transport medium of the Universal Viral Transport system and stored for over 3 months at various temperatures, after which virus titrations and quantitative analysis of the influenza hemagglutinin gene were performed.
This study provides important information for the handling of forensic virus specimens. The need for high-quality whole-genome sequence databases in microbial forensics. Microbial forensics is an important part of a strengthened capability to respond to biocrime and bioterrorism incidents to aid in the complex task of distinguishing between natural outbreaks and deliberate acts. The goal of a microbial forensic investigation is to identify and criminally prosecute those responsible for a biological attack, and it involves a detailed analysis of the weapon--that is, the pathogen.
The recent development of next-generation sequencing NGS technologies has greatly increased the resolution that can be achieved in microbial forensic analyses. It is now possible to identify, quickly and in an unbiased manner, previously undetectable genome differences between closely related isolates. This development is particularly relevant for the most deadly bacterial diseases that are caused by bacterial lineages with extremely low levels of genetic diversity.
Whole-genome analysis of pathogens is envisaged to be increasingly essential for this purpose. In a microbial forensic context, whole-genome sequence analysis is the ultimate method for strain comparisons as it is informative during identification, characterization, and attribution--all 3 major stages of the investigation--and at all levels of microbial strain identity resolution ie, it resolves the full spectrum from family to isolate. Given these capabilities, one bottleneck in microbial forensics investigations is the availability of high-quality reference databases of bacterial whole-genome sequences.
To be of high quality, databases need to be curated and accurate in terms of sequences, metadata, and genetic diversity coverage. The development of whole-genome sequence databases will be instrumental in successfully tracing pathogens in the future. Forensic biology is a sub-discipline of biological science with an amalgam of other branches of science used in the criminal justice system. These biological materials of human origin are rich source of proteins, carbohydrates, lipids, trace elements as well as water and, thus, provide a virtuous milieu for the growth of microbes.
The obstinate microbial growth augments the degradation process and is amplified with the passage of time and improper storage of the biological materials. Degradation of these biological materials carriages a huge challenge in the downstream processes of forensic DNA typing technique, such as short tandem repeats STR DNA typing. Microbial degradation yields improper or no PCR amplification, heterozygous peak imbalance, DNA contamination from non-human sources, degradation of DNA by microbial by-products, etc.
Consequently, the most precise STR DNA typing technique is nullified and definite opinion can be hardly given with degraded forensic exhibits. Thus, suitable precautionary measures should be taken for proper storage and processing of the biological exhibits to minimize their decaying process by micro-organisms. Current regulations in the United States stipulate that the microbial quality of waters used for consumption and recreational activities should be determined regularly by measuring microbial indicators of fecal pollution.
Hence, the microbial risk associated with these waters is A study focused on the effects of forensic participation on two specific traits--argumentativeness and verbal aggression. Two hundred eighty-one high school forensic students participating at a large western forensic tournament in the beginning of the academic year completed D. Infante's Argumentative and Verbal Aggression Scales.
Budowle, Bruce; Beaudry, Jodi A. The risk and threat of bioterrorism and biocrime have become a large concern and challenge for governments and society to enhance biosecurity. Law enforcement plays an important role in assessing and investigating activities involved in an event of bioterrorism or biocrime. Key to a successful biosecurity program is increased awareness and early detection of threats facilitated by an integrated network of responsibilities and capabilities from government, academic, private, and public assets.
To support an investigation, microbial forensic sciences are employed to analyze and characterize forensic evidence with the goal of attribution or crime scene reconstruction. Two different molecular biology-based assays — real time polymerase chain reaction PCR and repetitive element PCR — are described and demonstrate how molecular biology tools may be utilized to aid in the investigative process.
Technologies relied on by microbial forensic scientists need to be properly validated so that the methods used are understood and so that interpretation of results is carried out within the limitations of the assays. The three types of validation are preliminary, developmental, and internal. The first is necessary for rapid response when a threat is imminent or an attack has recently occurred. The latter two apply to implementation of routinely used procedures. The development of paleomicrobiology with new molecular techniques such as metagenomics is revolutionizing our knowledge of microbial evolution in human history.
The study of microbial agents that are concomitantly active in the same biological environment makes it possible to obtain a picture of the complex interrelations among the different pathogens and gives us the perspective to understand the microecosystem of ancient times. This research acts as a bridge between disciplines such as archaeology, biology, and medicine, and the development of paleomicrobiology forces archaeology to broaden and update its methods.
This chapter addresses the archaeological issues related to the identification of cemeteries from epidemic catastrophes typology of burials, stratigraphy, topography, paleodemography and the issues related to the sampling of human remains for biomolecular analysis.
Developments in the field of paleomicrobiology are described with the example of the plague. Because of its powerful interdisciplinary features, the paleomicrobiological study of Yersinia pestis is an extremely interesting field, in which paleomicrobiology, historical research, and archeology are closely related, and it has important implications for the current dynamics of epidemiology. Exploitation of microbial forensics and nanotechnology for the monitoring of emerging pathogens.
Emerging infectious diseases remain among the leading causes of global mortality. Traditional laboratory diagnostic approaches designed to detect and track infectious disease agents provide a framework for surveillance of bio threats. However, surveillance and outbreak investigations using such time-consuming approaches for early detection of pathogens remain the major pitfall.
Hence, reasonable real-time surveillance systems to anticipate threats to public health and environment are critical for identifying specific aetiologies and preventing the global spread of infectious disease. The current review discusses the growing need for monitoring and surveillance of pathogens with the same zeal and approach as adopted by microbial forensics laboratories, and further strengthening it by integrating with the innovative nanotechnology for rapid detection of microbial pathogens.
Such innovative diagnostics platforms will help to track pathogens from high risk areas and environment by pre-emptive approach that will minimize damages. The various scenarios with the examples are discussed where the high risk associated human pathogens in particular were successfully detected using various nanotechnology approaches with potential future prospects in the field of microbial forensics. Microbial soil community analyses for forensic science: Application to a blind test. Soil complexity, heterogeneity and transferability make it valuable in forensic investigations to help obtain clues as to the origin of an unknown sample, or to compare samples from a suspect or object with samples collected at a crime scene.
In a few countries, soil analysis is used in matters from site verification to estimates of time after death. However, up to date the application or use of soil information in criminal investigations has been limited. In particular, comparing bacterial communities in soil samples could be a useful tool for forensic science.
To evaluate the relevance of this approach, a blind test was performed to determine the origin of two questioned samples one from the mock crime scene and the other from a Both techniques discriminated well between soils from a single source, but a combination of both techniques was necessary to show that the origin was a mixture of soils.
This study illustrates the potential of applying microbial ecology methodologies in soil as an evaluative forensic tool. Drywall manufactured in China released foul odors attributed to volatile sulfur compounds. These included hydrogen sulfide, methyl mercaptan, and sulfur dioxide. Given that calcium sulfate is the main component of drywall, one would suspect bacterial reduction of sulfate to sulfide as the primary culprit.
However, when the forensics , i. Forensic evidence suggests that the transformation of elemental sulfur went through several abiological and microbial stages: Microbial DNA fingerprinting of human fingerprints: We tested the suitability of physical fingerprints for revealing human host information, with geographic inference as example, via microbial DNA fingerprinting.
We showed that the transient exogenous fingertip microflora is frequently different from the resident endogenous bacteria of the same individuals. While microbial species differed considerably in their frequency spectrum between fingerprint samples from volunteers in Europe and southern Asia, there was no clear geographic distinction between Staphylococcus strains in a cluster analysis, although bacterial genotypes did not overlap between both continental regions.
Our results, though limited in quantity, clearly demonstrate that the dynamic fingerprint microflora challenges human host inferences for forensic purposes including geographic ones. Overall, our results suggest that human fingerprint microflora is too dynamic to allow for forensic marker developments for retrieving human information.
Electronic supplementary material The online version of this article doi: Cost- effective forensic image enhancement. The forensic value of this examination in a major homicide investigation was apparent to the viewer. Equally clear was the potential for extracting evidence which is beyond the reach of conventional detection techniques. The cost of this technology in , however, was prohibitive, and well beyond the means of most police agencies. Twenty-two years later, a highly efficient means of image enhancement is easily within the grasp of most police agencies, not only for homicides but for any case application.
A PC workstation combined with an enhancement software package allows a forensic investigator to fully exploit digital technology. The goal of this approach is the optimization of the signal to noise ratio in images. Obstructive backgrounds may be diminished or eliminated while weak signals are optimized by the use of algorithms including Fast Fourier Transform, Histogram Equalization and Image Subtraction. An added benefit is the speed with which these processes are completed and the results known. The efficacy of forensic image enhancement is illustrated through case applications. We examined effects of participation and forensic context on 4-year-old children's testimony.
Children in "participant" and "police" conditions actively participated in games with a "babysitter"; each child in the "observer" condition watched a videotape of a child and the babysitter playing. Eleven days later, children were individually questioned about the event.
Before the interview began, children in the police condition talked to a police officer who said the babysitter might have done something bad. Comparison of participant- and observer-condition performance indicated that participation increased free-recall accuracy concerning actions that took place and lowered suggestibility. Comparison of participant- and police-condition performance indicated that forensic context led to increased error in free recall and additional comments to misleading questions.
However, forensic context also resulted in higher accuracy on an age-identification task and did not affect children's accuracy in answering abuse-related questions. Large-scale genomics projects are identifying biomarkers to detect human disease. Accurate characterization of metagenomic samples is dependent on accurate measurements of genetic variation between isolates with resolution down to strain level.
Often single biomarker sensitivity is augmented by use of multiple or panels of biomarkers. In parallel with single biomarker validation, advances in DNA sequencing enable analysis of entire genomes in a single run: Potentially, direct sequencing could be used to analyze an entire genome to serve as the biomarker for genome identification. However, genome variation and population diversity complicate use of direct sequencing, as well as differences caused by sample preparation protocols including sequencing artifacts and mistakes. As part of a Department of Homeland Security program in bacterial forensics , we examined how to implement whole genome sequencing WGS analysis as a judicially defensible forensic method for attributing microbial sample relatedness; and also to determine the strengths and limitations of whole genome sequence analysis in a forensics context.
Herein, we demonstrate use of sequencing to provide genetic characterization of populations: The nascent field of microbial forensics requires the development of diverse signatures as indicators of various aspects of the production environment of microorganisms. We have characterized isotopic relationships between Bacillus subtilis ATCC spores and their growth environment, using as a database the carbon, nitrogen, oxygen and hydrogen stable isotope ratios of a total of separate cultures of spores produced on a total of 32 different culture media.
We have analyzed variation within individual samples, between cultures produced in tandem, and between cultures produced in the same medium but at different times in the context of using stable isotope ratios as a signature for sample matching. We have correlated the stable isotope ratios of carbon, nitrogen, oxygen, and hydrogen of growth medium nutrients or water and spores and show examples of how these relationships can be used to exclude nutrient or water samples as possible growth substrates for specific cultures.
The power of stable isotope ratio data can be greatly enhanced by combining it with orthogonal datasets that speak to different aspects of an organism's production environment. We developed a Bayesian network that follows the causal relationship from culture medium recipe to spore elemental content as measured by secondary ion mass spectrometry SIMS , carbon and nitrogen stable isotope ratios, and to the presence of residual agar by electrospray ionization MS ESI-MS. The network was developed and tested on data from three replicate cultures of B. This network was able to characterize.
Vaginal microbial flora analysis by next generation sequencing and microarrays; can microbes indicate vaginal origin in a forensic context? Forensic analysis of biological traces generally encompasses the investigation of both the person who contributed to the trace and the body site s from which the trace originates. For instance, for sexual assault cases, it can be beneficial to distinguish vaginal samples from skin or saliva samples. In this study, we explored the use of microbial flora to indicate vaginal origin. Next, we selected candidate probes targeting genera or species and designed a microarray, with which we analysed a diverse set of samples; 43 DNA extracts from vaginal samples and 25 DNA extracts from samples from other body sites, including sites in close proximity of or in contact with the vagina.
Finally, we used the microarray results and next generation sequencing dataset to assess the potential for a future approach that uses microbial markers to indicate vaginal origin. Microarray analysis of a sample will then render a microbial flora pattern that is probably best analysed in a probabilistic approach. Evolving from discriminating distinct microbes to characterizing entire microbial communities on decomposing remains. The body of an animal encompasses a multitude of compositionally and functionally unique microbial environments, from the skin to the gastrointestinal system.
Each of these systems harbor microbial communities that have adapted in order to cohabitate with their specific host resulting in a distinct Kournikakis Resumen La microbiologia forense es una Entre las importantes razones que motivan una.
Quality Sample Collection, Handling, and Preservation for an Effective Microbial Forensics Program
Statistical modeling of the evaluation of evidence with the use of the likelihood ratio has a long history. It dates from the Dreyfus case at the end of the nineteenth century through the work at Bletchley Park in the Second World War to the present day. The development received a significant boost in with a seminal work by Dennis Lindley which introduced a Bayesian hierarchical random effects model for the evaluation of evidence with an example of refractive index measurements on fragments of glass.
Many models have been developed since then. The methods have now been sufficiently well-developed and have become so widespread that it is timely to try and provide a software package to assist in their implementation. Software for the Analysis and Implementation of Likelihood Ratios was funded by the European Network of Forensic Science Institutes through their Monopoly programme to develop a software package for use by forensic scientists world-wide that would assist in the statistical analysis and implementation of the approach based on likelihood ratios.
It is the purpose of this document to provide a short review of a small part of this history. Context effects are pervasive in forensic science, and are being recognized by a growing number of disciplines as a threat to objectivity. Cognitive processes can be affected by extraneous context information, and many proactive scientists are therefore introducing context-minimizing systems into their laboratories.
Forensic entomologists are also subject to context effects , both in the processes they undertake e. We stratify the risk of bias into low, medium, and high for the decisions and processes undertaken by forensic entomologists, and propose that knowledge of the time the deceased was last seen alive is the most potentially biasing piece of information for forensic entomologists. Effective use of forensic science in volume crime investigations: New scientific, technological and legal developments, particularly the introduction of national databases for DNA and fingerprints, have led to increased use of forensic science in the investigation of crime.
There is an assumption, and in some instances specific assertions, that such developments bring improvements either in broad criminal justice terms or more narrowly in terms of economic or practical efficiencies. The underlying presumption is that the new technological opportunities will be understood and effectively implemented.
This research investigates whether such increases in activity have also been accompanied by improvements in the effective use of forensic science. A systematic review of thirty-six reports published predominantly in England and Wales since the s, which have considered the use of forensic science in the investigation of volume crimes, was carried out.
These reports have identified a number of recurrent themes that influenced how effectively forensic science was used in investigations. The themes identified included forensic knowledge and training of investigators, communication and information exchange between specialists and investigators, timeliness of forensic results, interagency relationships and deployment of crime scene examiner resources. The research findings suggest that these factors continue to hinder the effective use of forensic science despite technological advances and this paper considers their potential causes. The forensic nursing in sexual assaults: Sexual assault was a ubiquitous and serious problem in our society.
The world's care centers and forensic associations, which were at the forefront of scientific research in sexual assaults, discussed the role of the Forensic Nursing in their early diagnosis and their prevention, but little has been written in literature regarding their appropriate management. This article focuses on the immunochemical laboratory investigation in diagnosis and prevention of its adverse effects in sexual assaults and the role of the Forensic Nursing played in this task. After a careful reading of all the material received from many of the care centers and the associations contacted, a Forensic Nursing Examination Program, with specific immunochemical address, is identified.
Effects of Participation and Forensic Context. This study, with 39 4-year-olds, found that children had better free recall accuracy and lowered suggestibility when they participated with a "babysitter" rather than observed a babysitter and child. Addition of forensic context by a policeman prior to questioning increased error in free recall but did not affect children's accuracy in…. Illustration and analysis of a coordinated approach to an effective forensic trace evidence capability.
An effective trace evidence capability is defined as one that exploits all useful particle types, chooses appropriate technologies to do so, and directly integrates the findings with case-specific problems. Limitations of current approaches inhibit the attainment of an effective capability and it has been strongly argued that a new approach to trace evidence analysis is essential. A hypothetical case example is presented to illustrate and analyze how forensic particle analysis can be used as a powerful practical tool in forensic investigations. The specifics in this example, including the casework investigation, laboratory analyses, and close professional interactions, provide focal points for subsequent analysis of how this outcome can be achieved.
This leads to the specification of five key elements that are deemed necessary and sufficient for effective forensic particle analysis: A coordinating role, absent in current approaches to trace evidence analysis, is essential to achieving these elements. However, the level of expertise required for the coordinating role is readily attainable. Some additional laboratory protocols are also essential.