Category Archives: Forensic DNA

Journal articles relating to forensic DNA including disaster victim identification.

New Genetics and Society Vol 33 no 3 Sep 2014 – Special Issue – Genetic Identification and the Response to Mass Fatalities

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Approaching disaster victim identification [Editorial]

This special issue is a response to a discussion concerning the role of DNA technology in the identification of bodies found following bush fires in Victoria in 2009.

Who knows who we are? Questioning DNA analysis in disaster victim identification

Identity, mass fatality and forensic genetics

Hidden in full sight: kinship, science and the law in the aftermath of the Srebrenica genocide

Ethical considerations in the use of DNA as a contribution toward the determination of identification in historic cases: considerations from the Western front

Naming the dead: DNA-based identification of historical remains as an act of care

Death duty – caring for the dead in the context of disaster

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Collecting and Analyzing DNA Evidence from Fingernails: A Comparative Study

Journal of Forensic Sciences Volume 59, Issue 5, pages 1343–1350, September 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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DNA and RNA analysis of blood and muscle from bodies with variable postmortem intervals

Forensic Science, Medicine, and Pathology September 2014, Volume 10, Issue 3, pp 322-328
The breakdown of DNA and RNA in decomposing human tissue represents a major obstacle for postmortem forensic molecular analysis. This study investigated the feasibility of performing PCR-based molecular analysis of blood and muscle tissue from 45 autopsy cases with defined postmortem intervals ranging from one to more than 14 days. It was not possible to collect blood from 38 % of the autopsy cases due to severe coagulation and hemolysis, whereas muscle tissue was available for all cases. PCR-amplifiable DNA could be extracted from 96 % of the frozen muscle specimens and from 93 % of the formalin fixed and paraffin embedded (FFPE) muscle specimens. A quality assessment of muscle-derived DNA showed increased fragmentation with advancing body decomposition and generally more fragmentation in DNA from FFPE tissue than in DNA from frozen tissue. It was possible to amplify 1,000 basepair (bp) DNA fragments from all samples with postmortem intervals below 3 days whereas 400–600 bp long fragments typically could be amplified from the most decomposed muscle specimens. RNA was less stable than DNA in postmortem muscle tissue, yet selected mRNA molecules could be detected by reverse-transcriptase PCR in all samples up to 3 days after death. We conclude that analysis of DNA from bodies with a wide postmortem interval range is usually possible whereas the consistency of RNA analyses decreases considerably 3 days postmortem. We showed that muscle tissue is a highly usable source of DNA and RNA for postmortem forensic molecular analysis as well as for retrospective research projects based on archived FFPE specimens.

Early evidence kits in sexual assault: an observational study of spermatozoa detection in urine and other forensic specimens

Forensic Science, Medicine, and Pathology September 2014, Volume 10, Issue 3, pp 336-343

Purpose

To determine the detection frequency of spermatozoa in early evidence kit specimens and in subsequent full forensic specimens in alleged sexual assault.

Methods

Observational cohort study of 100 consecutive alleged sexual assault cases, presenting in Western Australia between 19th July 2008 and 6th February 2012, with both early evidence kit and full forensic evidence specimen collections. Eighty-eight cases were included in the study. Smears from all forensic specimens were analyzed by light microscopy to determine the detection frequency and structural characteristics of spermatozoa. Patient demographic features, characteristics of the alleged assault and details and timing of forensic collections were also recorded.

Results

Spermatozoa were detected in early evidence kit specimens in 35 % (31/88) and in full forensic specimens in 42 % (37/88) of all cases (irrespective of type of alleged penetration). In alleged penile-vaginal penetration, spermatozoa were detected in early evidence kit specimens in 40 % (21/53) of cases when both first void urine and vulval gauze wipe were collected. Spermatozoa were detected in full forensic specimens in 45 % (31/69) of cases. Spermatozoa were detected in early evidence kit oral rinse specimens in 6 % (1/18) of cases of alleged penile-oral penetration and in early evidence perianal gauze wipe specimens in 33 % (2/6) cases of alleged penile-anal penetration. Spermatozoa were detected in the early evidence kit first void urine specimen in a single case, 11 % (1/9), in which the nature of the alleged assault was unknown. Spermatozoa were detected in early evidence kit specimens and not in full forensic specimens in 3 % (3/88) of cases.

Conclusions

Early evidence kit specimens are effective in recovery of spermatozoa, and in particular urine and vulval gauze wipe are worthwhile early forensic specimens for the detection of spermatozoa. Collection of early evidence specimens led to detection of spermatozoa-positive cases, which were not detected by subsequent full forensic specimen collection.

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Two Fagan nomograms for the (genetic) evidence in a judicial context

Australian Journal of Forensic Sciences Volume 46, Issue 3, 2014

While there are many computer programs that derive the likelihood ratio for genetic and other types of evidence, the Bayesian method of combination of prior probability coupled with the likelihood ratio, used by courts to ascertain posterior probability, has less support from software and other practical aids. Without proper instructions to a court, Bayes’ rule is either applied subconsciously by the judge, or prior probability is, by default, assigned a flat 50% probability by a forensic expert. In the worst case, it can be interpreted wrongly. A graphical representation using a nomogram is a proven way of representing Bayes’ theorem but remains underused in the field of forensics and the law. For this paper, I used the freeware package PyNomo to prepare two simple forensic nomograms allowing the graphical calculation of posterior probability by increasing or decreasing the prior probability due to evidence.

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FBI errors throw forensic convictions into question

New Scientist No 2981 6 August 2014

The FBI has admitted that its scientists may have made erroneous statements in thousands of criminal cases involving hair analysis

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Nondestructive Methods for Recovery of Biological Material from Human Teeth for DNA Extraction

Journal of Forensic Sciences 22 JUL 2014

The extraction of DNA from human skeletal remains applied to forensic, and evolutionary studies do not exclude risks, which are to be evaluated when working with unique specimens that could be damaged or even destroyed. In the present study were evaluated several nondestructive methods for recovering DNA instead of the most currently used pulverization method. Three different procedures to access inside the dental pieces (occlusal perforation, cervical perforation, and cervical cut) have been compared with the aim of recovering as many cell remains as possible to carry out a DNA extraction. Given the DNA quantitation results, a method was proposed that consists of a cervical cut to facilitate the access to the pulp cavity and a subsequent filing of the root canals down to the apex of the dental root. This methodology allows the recovery of both mitochondrial and nuclear DNA, with the minimum deterioration for the dental pieces.

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