A forensic investigation on the persistence of organic gunshot residues

Gunshot residues (GSR) are a potential form of forensic traces in firearm-related events. In most forensic laboratories, GSR analyses focus on the detection and characterisation of the inorganic components (IGSR), which are mainly particles containing mixtures of lead, barium and antimony originating from the primer. The increasing prevalence of heavy metal-free ammunition challenges the current protocols used for IGSR analysis. To provide complementary information to IGSR particles, the current study concentrated on the organic components (OGSR) arising from the combustion of the propellant. The study focused on four compounds well-known as being part of OGSR: ethylcentralite (EC), methylcentralite (MC), diphenylamine (DPA), N-nitrosodiphenylamine (N-nDPA). This study assessed the retention of these OGSR traces on a shooter’s hands. The overall project aim was to provide appropriate information regarding OGSR persistence, which can be suitable to be integrated into the interpretation framework of OGSR as recommended by the recent ENFSI Guideline for Evaluative Reporting in Forensic Science. The persistence was studied through several intervals ranging from immediately after discharge to four hours and two ammunition calibres were chosen: .40 S&W calibre, used by the NSW Police Force; and .357 Magnum, which is frequently encountered in Australian casework. This study successfully detected the compounds of interest up to four hours after discharge. The trends displayed a large decrease in the amount detected during the first hour. A large variability was also observed due to numerous factors involved in the production, deposition and collection of OGSR

Synthesis of 4-methyl-5-arylpyrimidines and 4-arylpyrimidines: route speci®c markers for the Leuckardt preparation of amphetamine, 4-methoxyamphetamine, and 4-methylthioamphetamine

Abstract General synthetic routes to 4-methyl-5-arylpyrimidines and 5-arylpyrimidines are described. 4-Benzylpyrimidine, 4-methyl-5-phenylpyrimidine, 4-(4-methoxybenzyl)pyrimidine, and 4-methyl-5-(4-methoxyphenyl)pyrimidine have been positively identi®ed as route-speci®c by-products in the Leuckardt preparations of amphetamine and 4-methoxyamphetamine. Using headspace solid phase microextraction (SPME) 4-(4-methoxybenzyl)pyrimidine and 4-methyl-5-(4-methoxyphenyl)pyrimidine have been identi®ed in illicit tablets containing 4-methoxyamphetamine. This is an indication that illicit laboratories use the Leuckardt method for the preparation of 4-methoxyamphetamine. Flatliner tablets containing 4-methylthioamphetamine have been screened for the presence of 4-(4-methylthiobenzyl)pyrimidine and 4-methyl-5-(4-methylthiophenyl)pyrimidine using both headspace and aqueous phase SPME. As these pyrimidines were not detected it would appear likely that illicit laboratories are not using the Leuckardt method for the preparation of 4-methylthioamphetamine.

Morphological identification of animal hairs: Myths and misconceptions, possibilities and pitfalls

The examination of hair collected from crime scenes is an important and highly informative discipline relevant to many forensic investigations. However, the forensic identification of animal (non-human) hairs requires different skill sets and competencies to those required for human hair comparisons. The aim of this is paper is not only to highlight the intrinsic differences between forensic human hair comparison and forensic animal hair identification, but also discuss the utility and reliability of the two in the context of possibilities and pitfalls. It also addresses and dispels some of the more popular myths and misconceptions surrounding the microscopical examination of animal hairs. Furthermore, future directions of this discipline are explored through the proposal of recommendations for minimum standards for the morphological identification of animal hairs and the significance of the newly developed guidelines by SWGWILD is discussed

Jumping to conclusions, general intelligence, and psychosis liability: findings from the multi-centre EU-GEI case-control study.

BACKGROUND: The 'jumping to conclusions' (JTC) bias is associated with both psychosis and general cognition but their relationship is unclear. In this study, we set out to clarify the relationship between the JTC bias, IQ, psychosis and polygenic liability to schizophrenia and IQ. METHODS: A total of 817 first episode psychosis patients and 1294 population-based controls completed assessments of general intelligence (IQ), and JTC, and provided blood or saliva samples from which we extracted DNA and computed polygenic risk scores for IQ and schizophrenia. RESULTS: The estimated proportion of the total effect of case/control differences on JTC mediated by IQ was 79%. Schizophrenia polygenic risk score was non-significantly associated with a higher number of beads drawn (B = 0.47, 95% CI -0.21 to 1.16, p = 0.17); whereas IQ PRS (B = 0.51, 95% CI 0.25-0.76, p < 0.001) significantly predicted the number of beads drawn, and was thus associated with reduced JTC bias. The JTC was more strongly associated with the higher level of psychotic-like experiences (PLEs) in controls, including after controlling for IQ (B = -1.7, 95% CI -2.8 to -0.5, p = 0.006), but did not relate to delusions in patients. CONCLUSIONS: Our findings suggest that the JTC reasoning bias in psychosis might not be a specific cognitive deficit but rather a manifestation or consequence, of general cognitive impairment. Whereas, in the general population, the JTC bias is related to PLEs, independent of IQ. The work has the potential to inform interventions targeting cognitive biases in early psychosis.EU HEALTH-F2-2009-24190

Multiple novel prostate cancer susceptibility signals identified by fine-mapping of known risk loci among Europeans

Genome-wide association studies (GWAS) have identified numerous common prostate cancer (PrCa) susceptibility loci. We have fine-mapped 64 GWAS regions known at the conclusion of the iCOGS study using large-scale genotyping and imputation in 25 723 PrCa cases and 26 274 controls of European ancestry. We detected evidence for multiple independent signals at 16 regions, 12 of which contained additional newly identified significant associations. A single signal comprising a spectrum of correlated variation was observed at 39 regions; 35 of which are now described by a novel more significantly associated lead SNP, while the originally reported variant remained as the lead SNP only in 4 regions. We also confirmed two association signals in Europeans that had been previously reported only in East-Asian GWAS. Based on statistical evidence and linkage disequilibrium (LD) structure, we have curated and narrowed down the list of the most likely candidate causal variants for each region. Functional annotation using data from ENCODE filtered for PrCa cell lines and eQTL analysis demonstrated significant enrichment for overlap with bio-features within this set. By incorporating the novel risk variants identified here alongside the refined data for existing association signals, we estimate that these loci now explain ∼38.9% of the familial relative risk of PrCa, an 8.9% improvement over the previously reported GWAS tag SNPs. This suggests that a significant fraction of the heritability of PrCa may have been hidden during the discovery phase of GWAS, in particular due to the presence of multiple independent signals within the same regio

Drosophila melanogaster odorant receptors as volatile compound detectors in forensic science:a proof-of-concept study

The ability to detect and identify substances based on the volatile compounds (odors) they emit is relied upon heavily for numerous investigative purposes. Animals have an innate olfactory sensitivity and selectivity that out-performs current instrumentation. This has led to immense interest in their employment as chemical sensors for a range of applications, including forensic science, both as whole organisms and as sensing elements in biosensors. Using electrophysiological and calcium imaging assays, this research examined the response of Drosophila melanogaster olfactory receptors (ORs) to odor compounds significant in forensic science and assessed their potential utility as volatile compound sensors. This investigation illustrated the different sensitivities, selectivities, and sensing features of individual ORs and demonstrated that their employment for detection purposes is feasible. While further research expanding on this study will be required to demonstrate the performance characteristics that an OR-based detection system will ultimately possess, this research provides an encouraging first step towards the goal of utilizing isolated biological ORs as volatile compound sensors in forensic science

Biological organisms as volatile compound detectors: A review

The detection and identification of volatile compounds is essential to the successful undertaking of numerous forensic analyses. Biological olfactory systems possess the extraordinary ability to not only detect many thousands of distinct volatile compounds (odors) but also to discriminate between them. Whole-organism biological sensors, such as detection canines, have been employed in forensic science as volatile compound detectors for many years. A variety of insects including bees, wasps, and moths, which have also been shown to detect volatile compounds of forensic significance, have been investigated for their potential application in field-based detection systems. While the fundamental aim for many developers of portable instruments is to replicate the remarkable ability of biological olfactory systems, such analytical equipment is yet to possess the detection and discriminatory powers achieved by biological sensors. Recent literature reveals an increasing interest in olfactory receptors - the biological components that impart olfactory ability - for detecting volatile compounds associated with forensically significant substances such as explosives and illicit drugs. This paper reviews the literature regarding the current, and potential future, use of biological organisms as sensors for forensic science applications. © 2013 Elsevier Ireland Ltd

Soil examination for a forensic trace evidence laboratory-Part 3:a proposed protocol for the effective triage and management of soil examinations

In the past, forensic soil examination was a routine aspect of forensic trace evidence examinations. The apparent need for soil examinations then went through a period of decline and with it the capability of many forensic laboratories to carry out soil examinations. In more recent years, interest in soil examinations has been renewed due-at least in part-to soil examinations contributing to some high profile investigations. However, much of this renewed interest has been in organisations with a primary interest in soil and geology rather than forensic science.We argue the need to reinstate soil examinations as a trace evidence sub-discipline within forensic science laboratories and present a pathway to support this aim. An examination procedure is proposed that includes: (i) appropriate sample collection and storage by qualified crime scene examiners; (ii) exclusionary soil examinations by trace evidence scientists within a forensic science laboratory; (iii) inclusionary soil examinations by trace evidence scientists within a forensic science laboratory; and (iv) higher-level examination of soils by specialist soil scientists and palynologists. Soil examinations conducted by trace evidence scientists will be facilitated if the examinations are conducted using the instrumentation routinely used by these examiners. Hence, the proposed examination protocol incorporates instrumentation in routine use in a forensic trace evidence laboratory. Finally, we report on an Australian soil scene variability study and a blind trial that demonstrate the utility of the proposed protocol for the effective triage and management of soil samples by forensic laboratories

Reinstating soil examination as a trace evidence sub-discipline

In the past, forensic soil examination was a routine aspect of forensic trace evidence examinations. However, the apparent need for soil examinations has diminished and with it the capability of forensic laboratories to carry out soil examination has been eroded. In recent years, due to soil examinations contributing to some high profile investigations, interest in soil examinations has been renewed. The need for, and suggested pathways to, the reinstatement of soil examinations as a trace evidence sub-discipline within forensic science laboratories is presented in this chapter. An examination procedure is also proposed that includes: appropriate sample collection and storage by qualified crime scene examiners; the preliminary examination of soils by trace evidence scientists within a forensic science laboratory; and the higher-level examination of soils by specialist geologists and palynologists. Soil examinations conducted by trace evidence scientists will be facilitated if the examinations are conducted using the instrumentation routinely used by these examiners. Trace evidence scientists routinely use a microspectrophotometer (MSP) for the colour analysis of forensic samples, including paint, fibres, inks and toners. This chapter also presents how a microspectrophotometer can be used to objectively measure the colour of forensic-sized soil samples as a demonstration as to how the proposed examination procedure can incorporate both trace evidence scientists within a forensic laboratory and specialist soil scientists