Category Archives: Forensic DNA

Journal articles relating to forensic DNA including disaster victim identification.

Extra-bodily DNA sampling by the police

Journal of Law and Medicine Vol 21 no 2 Dec 2013

Forensic investigators have statutory powers to take DNA samples directly from suspects’ bodies in certain circumstances but sometimes the powers fall short, legally or practically.  Police may then look for samples that have become separated from their suspects for one reason or another. No jurisdiction currently bars or even regulates this practice, which is instead loosely governed by laws on property, consent and evidence. This article argues that this lack of regulation undermines the entire system of forensic procedure laws.

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Collecting and Analyzing DNA Evidence from Fingernails: A Comparative Study

Journal of Forensic Sciences published online: 26 MAR 2014

Forensic practitioners and crime laboratories regularly collect and analyze fingernail evidence; however, the best techniques for processing such evidence have not been established. In this study, numerous aspects of fingernail evidence processing—collection of exogenous cells, transportation, purification of DNA, and STR analysis—were analyzed using fingernails harboring applied blood or epithelial cells from scratchings. Autosomal STR mixtures resulted when fingernails were soaked or swabbed, while scrapings rarely generated mixtures but exhibited allelic dropout. Y-STRs yielded single source profiles, with scrapings again showing dropout. A silica-based kit extraction recovered significantly more exogenous DNA than did organic extraction, neither of which was affected by nail polish. Swabbing nails in succession resulted in some cross-contamination from exogenous material, while transporting nails together did not, although there was loss of exogenous cells. Optimized nail processing produced complete Y-STR profiles of male volunteers from female fingernails following scratchings.

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Mutation models for DVI analysis

Forensic Science International: Genetics Volume 11, July 2014, Pages 85–95

In recent years, the use of DNA data for personal identification has become a crucial feature for forensic applications such as disaster victim identification (DVI). Computational methods to cope with these kinds of problems must be designed to handle large scale events with a high number of victims, obtaining likelihood ratios and posterior odds with respect to different identification hypotheses. Trying to minimize identification error rates (i.e., false negatives and false positives), a number of computational methods, based either on the choice between alternative mutation models or on the adoption of a different strategy, are proposed and evaluated. Using simulation of DNA profiles, our goal is to suggest which is the most appropriate way to address likelihood ratio computation in DVI cases, especially to be able to efficiently deal with complicating issues such as mutations or null alleles, considering that data about these latter are limited and fragmentary.

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Helping formulate propositions in forensic DNA analysis

Science & Justice  Available online 20 March 2014;   http://dx.doi.org/10.1016/j.scijus.2014.02.007

The Bayesian paradigm is the preferred approach to evidence interpretation. It requires the evaluation of the probability of the evidence under at least two propositions. The value of the findings (i.e., our LR) will depend on these propositions and the case information, so it is crucial to identify which propositions are useful for the case at hand. Previously, a number of principles have been advanced and largely accepted for the evaluation of evidence. In the evaluation of traces involving DNA mixtures there may be more than two propositions possible. We apply these principles to some exemplar situations. We also show that in some cases, when there are no clear propositions or no defendant, a forensic scientist may be able to generate explanations to account for observations. In that case, the scientist plays a role of investigator, rather than evaluator. We believe that it is helpful for the scientist to distinguish those two roles.

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Genetic mugshot recreates faces from nothing but DNA

New Scientist Peter Aldhous 20 March 2014

A MURDER has been committed, and all the cops have to go on is a trace of DNA left at the scene. It doesn’t match any profile in databases of known criminals, and the trail goes cold. But what if the police could issue a wanted poster based on a realistic “photofit” likeness built from that DNA?
Not if, but when, claim researchers who have developed a method for determining how our genes influence facial shape. One day, the technique may even allow us to gaze into the faces of extinct human-like species that interbred with our own ancestors.

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Linear amplification of target prior to PCR for improved low template DNA results

BioTechniques, Vol. 56, No. 3, March 2014, pp. 145–147

Forensic analysis of genetic material is often limited by the quantity and quality of DNA available for examination. Stochastic effects associated with low amounts of starting template can lead to a reduction in the quality of the result, making interpretation difficult. This paper presents an amplification method to copy target DNA in a linear fashion prior to short tandem repeat (STR) analysis to increase the available starting template without introducing the amplification bias seen in other methods used to increase the sensitivity of PCR. Results show that implementing the pre- PCR procedure allows for greater allele recovery in multiplex STR analysis compared with samples that were not subjected to prior processing.

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New book in the library collection – Written in Blood

Written in blood (2014) / Mike Silverman with Tony Thompson

As one of the UK’s leading forensic scientists, Mike Silverman has helped to identify and convict dozens of murderers, rapists, armed robbers, burglars and muggers, thanks to the evidence they – or their victims – unwittingly left behind at the scenes of their crimes. Mike Silverman started his career in the days when fingerprints were still kept on card files and DNA profiling was just a pipe dream, so ‘Written in blood’ is more than just a casebook – it is also a definitive history of the development of forensic science over the course of the past thirty-five years. From collecting blood samples at gangland executions to investigating forensic science failings, including in the murders of Rachel Nickell and Damilola Taylor, Mike Silverman’s unique career provides a fascinating insight into the ways forensic science is used to help solve real-life crimes. Packed with genuine crime scene photographs and original sketches, ‘Written in blood’ is the ultimate insider’s account of the fascinating world of forensic science.

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Limitations and recommendations for successful DNA extraction from forensic soil samples: A review

Science & Justice   Available online 11 March 2014;    http://dx.doi.org/10.1016/j.scijus.2014.02.006

Soil is commonly used in forensic casework to provide discriminatory power to link a suspect to a crime scene. Standard analyses examine the intrinsic properties of soils, including mineralogy, geophysics, texture and colour; however, soils can also support a vast amount of organisms, which can be examined using DNA fingerprinting techniques. Many previous genetic analyses have relied on patterns of fragment length variation produced by amplification of unidentified taxa in the soil extract. In contrast, the development of advanced DNA sequencing technologies now provides the ability to generate a detailed picture of soil microbial communities and the taxa present, allowing for improved discrimination between samples. However, DNA must be efficiently extracted from the complex soil matrix to achieve accurate and reproducible DNA sequencing results, and extraction efficacy is highly dependent on the soil type and method used. As a result, a consideration of soil properties is important when estimating the likelihood of successful DNA extraction. This would include a basic understanding of soil components, their interactions with DNA molecules and the factors that affect such interactions. This review highlights some important considerations required prior to DNA extraction and discusses the use of common chemical reagents in soil DNA extraction protocols to achieve maximum efficacy. Together, the information presented here is designed to facilitate informed decisions about the most appropriate sampling and extraction methodology, relevant both to the soil type and the details of a specific forensic case, to ensure sufficient DNA yield and enable successful analysis.

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Forensic Science Policy & Management: Volume 4, Issue 1-2, 2013

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Informing the Future: Discussion of Model Forensic Laboratories

Editorial

A “Gold Standard” Forensic Laboratory Model

What might a “gold standard” or perfect public forensic laboratory model be? Is there such a thing as a perfect model? Public forensic laboratories can be set up and operated in a variety of ways but no single, exemplary structure exists. This article addresses such questions about forensic laboratories as, “To which agency in local, state or federal government should a forensic laboratory be placed?”, “Is there such a thing as an appropriate level of service?”, and “Is the present system of delivering forensic science services within the criminal justice system the most efficient or effective arrangement?”, in the discussion of what a model forensic laboratory might look like.

The Forensic Sciences: Ideally, How Might They be Delivered?

It may reasonably be argued that the existing “non-system” delivery of forensic science services in the United States described in the report is because it was never planned or developed as a system. There never has been a conceptual model for an ideal, effective, efficient, reliable forensic science delivery system. Developing such a model would be a substantial challenge and would require a significant effort by knowledgeable creative stakeholders. One such model, the conceptualization of an ideal forensic science delivery system, is described in this article.

Criteria and Concepts for a Model Forensic Science Laboratory

The National Academy of Sciences Forensic Science Committee issued a report in 2009 that raised a number of issues concerning forensic science. One of the major criticisms of the report concerned the nature of forensic science laboratories in the U.S. The report focused on the fragmentation of the system, the lack of universal accreditation and certification of laboratories and personnel, the management and funding models and a serious lack of standards in reporting, terminology, and methods of analysis. The question thus arises; if one could design the model of a forensic science laboratory, what should it look like? What should its management structure be? Should it be affiliated with a law enforcement agency or independent? Must it be accredited? Must all of the scientists who work in the lab be certified? What standards should be developed that govern the operation of the laboratory? What types of training should be put in place? The answers to these and other, similar questions can provide a framework for the design and implementation of a model forensic science laboratory. In the opinion of the author, such a lab would be independent of law enforcement, accredited and certified, be independently funded by the jurisdiction within which it lies, have standardized, documented training protocols, standardized, validated methods of analysis and a role for research into new methods of analysis. These and other issues are discussed.

A Review and Commentary on the Model Forensic Science Laboratory

Forensic science is a unique discipline; it is like no other professional enterprise. First and foremost, our work is done in an adversarial system of the courts. In the United States, this poses a unique juxtaposition that places professionals in science and the law to debate truth versus justice. Secondarily, the producers of forensic science deliverables are considered “high reliability organizations” or HROs. We are responsible for the production and transformation of information from raw materials that are insulted, degraded, and contaminated collected from non-pristine and non-controlled environments and have to turn that into “perfect” information. No other industry or enterprise has this level of difficulty or responsibility in producing its work product. This article is a response to the three model proposals in this issue, offering a commentary and vision of the future for a model forensic science laboratory.

10 Criteria Defining a Model Forensic Science Laboratory

This article attempts to answer the question: If it had to be done over again, knowing what is known now, how would the ideal forensic science laboratory be constructed, organized, and operated? A project was initiated to answer this question by the Laura and John Arnold Foundation in Houston, Texas, which brought together select, influential, and highly recognized forensic science icons to discuss and document the elements of the model forensic science laboratory—to the extent that such a model could actually exist. Barry A.J. Fisher, Doug M. Lucas, and Jay A. Siegel (the project team) each authored, independently, a manuscript outlining what they believed were the critical elements or criteria defining the model forensic science laboratory. Once the aforementioned manuscripts were completed, the project team requested that this article be written to independently review, consolidate, and comment on the work of the project team writers.

New in the collection – Forensic Technologies Market 2013-2019

Forensic technologies market: (physical crime forensics, laboratory forensics, portable forensics, forensic tools and products) Industry analysis, size, share, growth, trends and forecast, 2013-2019

This report studies the market for forensic technologies from the point of view of the various services offered in the market. The overall forensic technologies/services market is classified into DNA profiling, biometrics/fingerprints analysis, chemical (drugs/explosives/toxicology) analysis and firearms identification and analysis. Each of these segments is further divided into different sub-segments based on the service type. The forensic technologies/services market is also studied from the aspect of location or point of delivery of forensic technologies/services. The market size and forecast for the period 2011 – 2019, in terms of USD million, considering 2012 as the base year has been provided for each segment and sub-segment in the report. The compound annual growth rate (CAGR) for each segment has been provided for the forecast period from 2013 – 2019.  more

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