Detection of Cutting Agents in Drug‐Positive Seized Exhibits within the United States

The following report summarizes a study performed on seized drug exhibits collected in two U.S. states to evaluate the presence and identification of cutting agents. Aliquots of seized drug materials from Kentucky (n = 200) and Vermont (n = 315) were prepared using a dilute‐and‐shoot procedure. Initial analysis was performed using gas chromatography–mass spectrometry (GC‐MS) followed by analysis using liquid chromatography quadrupole time‐of‐flight mass spectrometry (LC‐QTOF). Active compounds detected overall included caffeine (31.0%), quinine/quinidine (24.7%), levamisole (11.6%), acetaminophen, (8.2%) and procaine (8.2%). These compounds were found with several drugs of abuse, such as heroin, fentanyl, methamphetamine, and cocaine. This novel information about cutting agents used to dilute or alter drugs of abuse is important to criminal investigations and in the management of acute intoxications at health centers. However, common methodologies for analysis and standard reporting practices frequently do not include cutting agents, resulting in lacking or inadequate information regarding prevalence of these substances.     

Heat and let dye: Part II – Rapid heat-fixing of blood traces

Blood-contaminated shoeprints and footmarks contain valuable operational information as they may bind an individual who stepped in the crime scene with the incident and not merely with the location. As determining the age of a bloodstain remains a challenge, while processing the scene, it is difficult to determine whether the blood is completely, or partially, dry. Thus, executing a dye staining protocol may wash these marks away as they might still be soluble. However, to meet this challenge, it is possible to fix blood marks using heat. This study aims to find a solution for floor surfaces covered by heavier blood traces (shoeprints and footmarks). For this purpose, a new pseudo-operating device was constructed for examining the blood-fixing process of both mentioned trace types. Two trials were performed with depletion marks. The results revealed that fully developed fresh and heavily blood deposits were obtained by heating to 200°C for 7.5 min using the fixing device, followed by a staining protocol using amido black solution. The achieved sharp resolution of the examined bloody prints demonstrates that in certain cases the dehydration mechanism of heating is preferred over precipitating the proteins attributed to 5-sulfosalycilic acid; thus, reducing the risk of washing blood evidence while processing the crime scene.     

Uncertainty about the true source. A note on the likelihood ratio at the activity level

This paper focuses on likelihood ratio based evaluations of fibre evidence in cases in which there is uncertainty about whether or not the reference item available for analysis - that is, an item typically taken from the suspect or seized at his home - is the item actually worn at the time of the offence. A likelihood ratio approach is proposed that, for situations in which certain categorical assumptions can be made about additionally introduced parameters, converges to formula described in existing literature. The properties of the proposed likelihood ratio approach are analysed through sensitivity analyses and discussed with respect to possible argumentative implications that arise in practice.     

Bayesian networks and the value of the evidence for the forensic two-trace transfer problem*

Forensic scientists face increasingly complex inference problems for evaluating likelihood ratios (LRs) for an appropriate pair of propositions. Up to now, scientists and statisticians have derived LR formulae using an algebraic approach. However, this approach reaches its limits when addressing cases with an increasing number of variables and dependence relationships between these variables. In this study, we suggest using a graphical approach, based on the construction of Bayesian networks (BNs). We first construct a BN that captures the problem, and then deduce the expression for calculating the LR from this model to compare it with existing LR formulae. We illustrate this idea by applying it to the evaluation of an activity level LR in the context of the two-trace transfer problem. Our approach allows us to relax assumptions made in previous LR developments, produce a new LR formula for the two-trace transfer problem and generalize this scenario to n traces.     

Specifying the role of exposure to violence and violent behavior on initiation of gun carrying: a longitudinal test of three models of youth gun carrying

Two waves of longitudinal data from 1,049 African American youth living in extreme poverty are used to examine the impact of exposure to violence (Time 1) and violent behavior (Time 1) on first time gun carrying (Time 2). Multivariate logistic regression results indicate that (a) violent behavior (Time 1) increased the likelihood of initiation of gun carrying (Time 2) by 76% after controlling for exposure to violence at Time 1, which is consistent with the stepping stone model of youth gun carrying, and (b) youth who were both exposed to violence at Time 1 and engaged in violent behavior at Time 1 were more than 2.5 times more likely to initiate gun carrying at Time 2 compared to youth who had neither of these characteristics, which supports the cumulative risk model of youth gun carrying. The authors discuss the implications of these findings in clarifying the role of violence in the community on youth gun carrying and the primary prevention of youth gun violence.     

Differential Effects of Adult Court Transfer on Juvenile Offender Recidivism

Prior research indicates that adolescent offenders transferred to adult court are more likely to recidivate than those retained in the juvenile system. The studies supporting this conclusion, however, are limited in addressing the issue of heterogeneity among transferred adolescents. This study estimates the effect of transfer on later crime using a sample of 654 serious juvenile offenders, 29% of whom were transferred. We use propensity score matching to reduce potential selection bias, and we partition the sample on legal characteristics to examine subgroup effects. We find an overall null effect of transfer on re-arrest, but evidence of differential effects of transfer for adolescents with different offending histories. These results suggest that evaluating the effects of transfer for all transferred adolescents together may lead to misguided policy conclusions.     

Examining Systematic Crime Reporting Bias Across Three Immigrant Generations: Prevalence,Trends, and Divergence in Self-Reported and Official Reported Arrests

Objective

Mounting evidence reveals that foreign-born, first generation immigrants have significantly lower levels of criminal involvement compared to their US-born, second and third-plus generation peers. This study investigates whether this finding is influenced by differential crime reporting practices by testing for systematic crime reporting bias across first, second, and third-plus generation immigrants.

Methods

This study draws on data from the Pathways to Desistance Study, a longitudinal investigation of the transition from adolescence to young adulthood among a sample of serious adolescent offenders. Self-reported and official reports of arrest are compared longitudinally across ten waves of data spanning 7 years from adolescence into young adulthood for nearly 1300 adjudicated males and females.

Results

This study reveals a high degree of correspondence between self-reports of arrest and official reports of arrest when compared within groups distinguished by immigrant generation. Longitudinal patterns of divergence, disaggregated by under-reporting and over-reporting, in self- and official-reports of arrest indicated a very high degree of similarity regardless of immigrant generation. We found no evidence of systematic crime reporting bias among foreign-born, first generation immigrants compared to their US-born peers.

Conclusions

First generation immigrants are characterized by lower levels of offending that are not attributable to a differential tendency to under-report their involvement in crime.