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Durdle A.,La Trobe University | Mitchell R.J.,La Trobe University | van Oorschot R.A.H.,Office of the Chief Forensic Scientist
Journal of Forensic Sciences

As human DNA profiles can be obtained from blow fly artifacts, this study aimed to establish the feeding preferences of Lucilia cuprina (Wiedemann) blow flies when offered human biological fluids and nonhuman food sources. One-day-old and 3-day-old blow flies of both sexes were simultaneously offered human blood, semen and saliva, pet food, canned tuna and honey, and the number and length of visits documented over 6 h. One-day-old flies visited pet food and honey most often, but stayed longest on honey and semen. Three-day-old flies visited semen and pet food most often, and stayed longest on these food sources. Blood and saliva were the least preferred options for all flies. Overall, flies preferred dry blood and semen to the wet forms. These findings demonstrate that even when other food sources are available, flies at a crime scene may feed on human biological fluids if present, potentially transferring human DNA. © 2016 American Academy of Forensic Sciences. Source

Found B.,Office of the Chief Forensic Scientist
Australian Journal of Forensic Sciences

It has been almost a decade since a paradigm shift in the forensic identification sciences was predicted. This shift was seen as an inevitable response to the mounting pressure resulting from scientific criticisms from both legal and academic camps. For most of the identification disciplines, the traditional paradigm has proven remarkably resistant to change. There has, however, been a healthy increase in research engagement relating to studies focused on the role that human perceptual and cognitive processes play in deciphering traditional forms of forensic evidence. The greatest cognitive research efforts in recent times have been directed toward the potential for bias to influence the outcomes of forensic examinations. The role of cognitive research is far more wide-reaching however, and is making important contributions to understanding models of interpretation and reporting, to assessing the characteristics of forensic competency and in identifying flawed constructs in subjective examination approaches. The challenge for our profession is to encourage cognitive scientists to assist us in understanding the characteristics of our claimed expertise, to make our resources available to detailed studies in spite of our casework demands, and ultimately to develop a culture prepared to change the way we go about our work. © 2014 Australian Academy of Forensic Sciences. Source

Dewhurst T.N.,La Trobe University | Dewhurst T.N.,Document Examination Unit | Found B.,La Trobe University | Ballantyne K.N.,Office of the Chief Forensic Scientist | Rogers D.,La Trobe University
Forensic Science International

Expertise studies in forensic handwriting examination involve comparisons of Forensic Handwriting Examiners' (FHEs) opinions with lay-persons on blind tests. All published studies of this type have reported real and demonstrable skill differences between the specialist and lay groups. However, critics have proposed that any difference shown may be indicative of a lack of motivation on the part of lay participants, rather than a real difference in skill. It has been suggested that qualified FHEs would be inherently more motivated to succeed in blinded validation trials, as their professional reputations could be at risk, should they perform poorly on the task provided. Furthermore, critics suggest that lay-persons would be unlikely to be highly motivated to succeed, as they would have no fear of negative consequences should they perform badly. In an effort to investigate this concern, a blind signature trial was designed and administered to forty lay-persons. Participants were required to compare known (exemplar) signatures of an individual to questioned signatures and asked to express an opinion regarding whether the writer of the known signatures wrote each of the questioned signatures. The questioned signatures comprised a mixture of genuine, disguised and simulated signatures. The forty participants were divided into two separate groupings. Group 'A' were requested to complete the trial as directed and were advised that for each correct answer they would be financially rewarded, for each incorrect answer they would be financially penalized, and for each inconclusive opinion they would receive neither penalty nor reward. Group 'B' was requested to complete the trial as directed, with no mention of financial recompense or penalty. The results of this study do not support the proposition that motivation rather than skill difference is the source of the statistical difference in opinions between individuals' results in blinded signature proficiency trials. © 2014. Source

Freitag C.,Business Services Group | Found B.,Office of the Chief Forensic Scientist
Australian Journal of Forensic Sciences

Forensic laboratories traditionally focus on the development of scientific excellence to gain and maintain expertise and capability for their core purpose with respect to the provision of sound, impartial analysis of potential evidence, while managing increasingly tight budgets and growing demand. One downside to this primary focus is the lower prioritisation afforded to strategic and operational planning, despite its potential to substantially improve service delivery and enhance efficiency. Here, we focus on traditional planning models used by forensic laboratories and their shortfalls, and we examine options for improvement. Contemporary planning methodologies are assessed for their applicability and one improved planning model is developed and its potential benefits are evaluated. © 2016 Copyright held by the State of Victoria, Australia, through the Victoria Police Forensic Services Department. Source

Szkuta B.,Deakin University | Harvey M.L.,Deakin University | Ballantyne K.N.,Office of the Chief Forensic Scientist | Ballantyne K.N.,La Trobe University | Van Oorschot R.A.H.,Office of the Chief Forensic Scientist
Forensic Science International: Genetics

The introduction of profiling systems with increased sensitivity has led to a concurrent increase in the risk of detecting contaminating DNA in forensic casework. To evaluate the contamination risk of tools used during exhibit examination we have assessed the occurrence and level of DNA transferred between mock casework exhibits, comprised of cotton or glass substrates, and high-risk vectors (scissors, forceps, and gloves). The subsequent impact of such transfer in the profiling of a target sample was also investigated. Dried blood or touch DNA, deposited on the primary substrate, was transferred via the vector to the secondary substrate, which was either DNA-free or contained a target sample (dried blood or touch DNA). Pairwise combinations of both heavy and light contact were applied by each vector in order to simulate various levels of contamination. The transfer of dried blood to DNA-free cotton was observed for all vectors and transfer scenarios, with transfer substantially lower when glass was the substrate. Overall touch DNA transferred less efficiently, with significantly lower transfer rates than blood when transferred to DNA-free cotton; the greatest transfer of touch DNA occurred between cotton and glass substrates. In the presence of a target sample, the detectability of transferred DNA decreased due to the presence of background DNA. Transfer had no impact on the detectability of the target profile, however, in casework scenarios where the suspect profiles are not known, profile interpretation becomes complicated by the addition of contaminating alleles and the probative value of the evidence may be affected. The results of this study reiterate the need for examiners to adhere to stringent laboratory cleaning protocols, particularly in the interest of contamination minimisation, and to reduce the handling of items to prevent intra-item transfer. © 2015 Elsevier Ireland Ltd. Source

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