Investigative studies into the recovery of DNA from improvised explosive device containers

Apprehending those who utilize improvised explosive devices (IEDs) is a national priority owing to their use both domestically and abroad. IEDs are often concealed in bags, boxes, or backpacks to prevent their detection. Given this, the goal of the research presented was to identify IED handlers through postblast DNA recovery from IED containers. Study participants were asked to use backpacks for 11 days, after which they served as containers for pipe bombs. Eleven postdeflagration backpack regions likely to be handled were swabbed and analyzed via mini-short tandem repeats (miniSTRs) and alleles were called blind. An experimental consensus method was examined in which profiles from all regions were considered, to help identify spurious drop-in/out. Results were correct for all loci, except one that remained ambiguous. The results show that recovering DNA from IED containers is a viable approach for aiding in the identification of those who may have been involved in an IED event.     

GC-MS and GC-IRD analysis of 2-, 3- and 4-methylmethamphetamine and 2-, 3- and 4-methylamphetamine

4-Methylmethamphetamine has been detected in samples submitted for analysis in several states throughout Australia. Six ring substituted methyl isomers of methamphetamine and amphetamine were synthesised and analysed. As the regioisomeric 2-, 3- and 4-methylmethamphetamine and 2-, 3- and 4-methylamphetamine have virtually identical mass spectra, the use of MS is an ineffective technique to discriminate between these closely related compounds. We set out to determine whether the regioisomers could be differentiated by a combination of GC-MS, acetyl derivatisation and GC-IRD. We demonstrate that the three isomers of methylmethamphetamine and methylamphetamine can be separated by GC, and a combination of acetyl derivatisation and vapour phase IR can identify the specific ring substituted compound.     

Score-based likelihood ratios for handwriting evidence

Score-based approaches for computing forensic likelihood ratios are becoming more prevalent in the forensic literature. When two items of evidential value are entangled via a scorefunction, several nuances arise when attempting to model the score behavior under the competing source-level propositions. Specific assumptions must be made in order to appropriately model the numerator and denominator probability distributions. This process is fairly straightforward for the numerator of the score-based likelihood ratio, entailing the generation of a database of scores obtained by pairing items of evidence from the same source. However, this process presents ambiguities for the denominator database generation - in particular, how best to generate a database of scores between two items of different sources. Many alternatives have appeared in the literature, three of which we will consider in detail. They differ in their approach to generating denominator databases, by pairing (1) the item of known source with randomly selected items from a relevant database; (2) the item of unknown source with randomly generated items from a relevant database; or (3) two randomly generated items. When the two items differ in type, perhaps one having higher information content, these three alternatives can produce very different denominator databases. While each of these alternatives has appeared in the literature, the decision of how to generate the denominator database is often made without calling attention to the subjective nature of this process. In this paper, we compare each of the three methods (and the resulting score-based likelihood ratios), which can be thought of as three distinct interpretations of the denominator proposition. Our goal in performing these comparisons is to illustrate the effect that subtle modifications of these propositions can have on inferences drawn from the evidence evaluation procedure. The study was performed using a data set composed of cursive writing samples from over 400 writers. We found that, when provided with the same two items of evidence, the three methods often would lead to differing conclusions (with rates of disagreement ranging from 0.005 to 0.48). Rates of misleading evidence and Tippet plots are both used to characterize the range of behavior for the methods over varying sized questioned documents. The appendix shows that the three score-based likelihood ratios are theoretically very different not only from each other, but also from the likelihood ratio, and as a consequence each display drastically different behavior.     

Tattoo frequency and types among homicides and other deaths, 2007-2008: a matched case-control study

An estimated 25% of the US population aged 18 to 50 years has a tattoo, which have been associated with markers of high-risk behaviors including alcohol and drug use, violence, carrying weapons, sexual activity, eating disorders, and suicide. This study compares tattoo prevalence and type in a homicide population to those of an age-, race-, and sex-matched control group of nonhomicide deaths. The data for this study were abstracted from autopsy records maintained by the Jefferson County Alabama Coroner/Medical Examiner's Office for the years 2007 and 2008. Odds ratios and 95% confidence intervals for the association between homicide and tattoo presence and characteristics were calculated using conditional logistic regression. There was no association between tattoo presence and death by homicide; however, among blacks, memorial tattoos were significantly more common among homicides compared with other types of deaths (odds ratio, 2.50; 95% confidence interval, 1.10-5.68). The results of the current study suggest that specific types of tattoos, but not all tattoos, may be risk factors for homicide. Other factors, such as race and lifestyle, along with tattoos may need to be considered.     

Space–Time Modeling of Insurgency and Counterinsurgency in Iraq

The US and its Coalition partners concluded combat operations in Iraq in August 2010. Rather surprisingly, little empirical evidence exists as to the factors that contributed to the ebb and flow in levels of violence and the emergence and disappearance of hot spots of hostilities during the campaign. Building upon a tradition of criminology scholarship, recent work demonstrates that Improvised Explosive Device (IED) attacks are clustered in space and time and that these trends decay in a manner similar to that observed in the spread of disease and crime. The current study extends this work by addressing a key potential correlate of these observed patterns across Iraq—namely, the timing and location of a variety of Coalition counterinsurgency (COIN) operations. This is achieved by assessing the co-evolving space–time distributions of insurgency and counterinsurgency in the first 6 months of 2005. To do so, we employ a novel analytic technique that helps us to assess the sequential relationship between these two event types. Our analyses suggest that the number of COIN operations that follow insurgent IED attacks (moderately) exceeds expectation (assuming that events are independent) for localities in the vicinity of an attack. This pattern is more consistent than is observed for the relationship in the opposite direction. The findings also suggest that less discriminatory COIN operations are associated with an elevated occurrence of subsequent insurgency in the vicinity of COIN operations in the medium to long term, whilst for more discriminatory and capacity-reducing COIN operations the reverse appears to be true.     

Expert Testimony of the Battered Person Syndrome, Defendant Gender, and Sexual Orientation in a Case of Duress: Evaluating Legal Decisions

The current study examined the utility of expert testimony of the battered person syndrome (BPS) in a case of duress and the extent to which defendant gender, defendant sexual orientation, and participant gender influence mock jury decisions in a case of duress. Participants (N?=?413) read a scenario based on U.S. v. Dixon (2006) and answered questions assessing verdict, guilt, sentence length, duress legal elements, and attributes typically ascribed to victims of abuse. Results showed heterosexual female defendants were assigned the lowest sentences and met more of the legal elements of duress (i.e., were coerced, more likely to be believed, and purchased a gun to prevent harm) and attributes (i.e., experienced severe abuse, learned helplessness) compared to other defendants. When mock jurors received expert testimony, they provided lower rates of guilt and sentencing for defendants. Results also showed the inclusion of BPS expert testimony increased ratings for many of the legal elements of duress and attributes typically associated with intimate partner violence. In addition, results suggested that while heterosexual female defendants are more likely to be believed in a case of duress, expert testimony of BPS is helpful to all defendants. Limitations and future directions for research and practice are discussed.     

Toxicology and Circumstances of Death of Homicide Victims in New South Wales, Australia 1996–2005

Abstract:  To determine the prevalence and circumstances of psychoactive substances amongst homicide victims, 485 consecutive cases autopsied at the NSW Department of Forensic Medicine (1/1/1996–12/31/2005) were analyzed. Substances were detected in 62.6% of cases, and illicit drugs in 32.8%. Alcohol, cannabis, opioids, and psychostimulants were most commonly detected. Alcohol and cannabis were both more prevalent amongst males. Mean ages were significantly younger for decedents who tested positive for a substance and for an illicit drug. Cases where death resulted from a physical altercation were more likely to have had alcohol and cannabis present. Illicit drugs were prominent amongst firearms deaths. The proportion of alcohol positive cases increased from 25.0% on Monday to 49.4% for Saturdays/Sundays. Alcohol was more common in incidents in the 0001–0600 h and 1800–2400 h periods. Psychoactive substances appear to substantially increase the risk of homicide, although there are important differences between drug classes in the circumstances of such incidents.     

Preparing for unwanted events: Instances of international political terrorism∗

The problems posed by international political terrorism, the likely performances of governments facing such challenges, and advisable preparatory coping strategies all benefit from systematic consideration of the experience, provided by practices and analyses of attempts to avoid and manage other forms of international crises. This paper pursues such a perspective to supplement more familiar approaches that use police and disaster amelioration points of departure.

The broader experience of international crises makes it clear that the problems are less ones of incident management than of prolonged competition for an image of political legitimacy and efficacy. Accordingly, recommendation for analysis and planning are made with emphasis on inventory of existent management capacities and decision processes, clarification of alternative political consequences, nonintrusive technology fixes, bargaining and indemnification policy options; and diagnostic gaming.