Patterns of Aggressive Behavior and Peer Victimization from Childhood to Early Adolescence: A Latent Class Analysis

The developmental period characterized by the transition from childhood and elementary school to early adolescence and middle school has been associated with increases in aggressive behavior and peer victimization. Few longitudinal studies, however, have examined the stability of aggression and victimization during this critical transition. This study uses latent class analysis (LCA) to examine patterns of aggressive behavior and victimization during the transition to middle school among urban, public school students (N = 458; Girls = 53%; Latino/a = 53%; M age at t1 = 10.2 years). Independent LCA models were conducted using self-reported data assessing subjects’ involvement in aggressive conduct and victimization during the spring semesters of grades four, five, and six. Elementary school students in the fourth grade initially belonged to one of four groups identified as aggressor, victim, aggressor-victim, and uninvolved latent classes. Contrary to prior research, membership in these classes changed significantly by the time students completed their first year of middle school with most youth participating in episodes of aggression and victimization during the transition. Six common paths that describe patterns of aggressive behavior and victimization from the last two years of elementary school to the first year of middle school were found. Findings are discussed in the context of social dominance theory and prior research that has found greater stability in aggression and victimization among early adolescents.     

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.     

Is Plea Bargaining in the “Shadow of the Trial” a Mirage?

It has been well established that a ??plea discount?? or ??trial penalty?? exists, such that defendants who plead guilty receive significant sentencing discounts relative to what they would receive if convicted at trial. Theorists argue that the exact value of this plea discount is determined by bargaining ??in the shadow of a trial,?? meaning that plea decision-making is premised on the perceived probable outcome of a trial. In trials, the strength of the evidence against defendants greatly impacts the probability of conviction. In the present study, we estimate the probability of conviction at the individual level for those who pled guilty. We find that, contrary to the shadow of the trial model, evidentiary factors either do not impact or negatively impact the probability of conviction, which stands in stark contrast to the impact evidence has at trials. These findings suggest that plea bargain decision-making may not occur in the shadow of the trial.     

Analysis of artificially degraded DNA using STRs and SNPs--results of a collaborative European (EDNAP) exercise

Recently, there has been much debate about what kinds of genetic markers should be implemented as new core loci that constitute national DNA databases. The choices lie between conventional STRs, ranging in size from 100 to 450 bp; mini-STRs, with amplicon sizes less than 200 bp; and single nucleotide polymorphisms (SNPs). There is general agreement by the European DNA Profiling Group (EDNAP) and the European Network of Forensic Science Institutes (ENFSI) that the reason to implement new markers is to increase the chance of amplifying highly degraded DNA rather than to increase the discriminating power of the current techniques. A collaborative study between nine European and US laboratories was organised under the auspices of EDNAP. Each laboratory was supplied with a SNP multiplex kit (Foren-SNPs) provided by the Forensic Science Service, two mini-STR kits provided by the National Institute of Standards and Technology (NIST) and a set of degraded DNA stains (blood and saliva). Laboratories tested all three multiplex kits, along with their own existing DNA profiling technique, on the same sets of degraded samples. Results were collated and analysed and, in general, mini-STR systems were shown to be the most effective. Accordingly, the EDNAP and ENFSI working groups have recommended that existing STR loci are reengineered to provide smaller amplicons, and the adoption of three new European core loci has been agreed.     

Temporal Linkages in Violent and Nonviolent Criminal Activity

Research on the temporal distribution of criminal behavior has highlighted two distinct mechanisms—population heterogeneity and state dependence. Most of this work indicates that long-term patterns of criminal offending reflect a mixture of stable individual differences and the causal effect of life events and experiences. Yet several ambiguities remain. Among the most important of these problems is whether both population heterogeneity and state dependence processes operate for different types of offending. We use longitudinal official record and self-report data for violent and non-violent offending activity from the Rochester Youth Development Study to address these ambiguities.     

Preparation of degraded human DNA under controlled conditions

DNA typing through analysis of short tandem repeats (STRs) and mitochondrial DNA (mtDNA) by means of the polymerase chain reaction (PCR) and sequencing are the common methods for the forensic identification of persons and reconstruction of kinship, especially when skeletal human remains have to be analyzed. Furthermore, samples typically found at crime scenes may be both quantitatively and qualitatively inadequate since they may contain very scarce and often degraded DNA due to exposure to heat, light, humidity, and microorganisms. In order to improve the performance of STR typing technology in those cases where DNA availability is limited, it would be desirable to have a source of degraded DNA with known properties. For this purpose, we have developed a method to prepare artificially degraded DNA under controlled conditions. By treatment of genomic DNA with sonication and DNAse I we have produced DNA fragments within a defined range of lengths. STR typing of this degraded DNA with a commercially available multiplex kit could only produce partial profiles as indicated by the absence of STR alleles with sizes >200 bp. This artificially degraded DNA can be used for the improvement and standardization of STR typing protocols when only highly degraded DNA is available for analysis.     

Using STR analysis to detect human DNA from exploded pipe bomb devices

This study investigated the possibility of recovering a bomb assembler's DNA from an exploded pipe bomb device. Metal and polyvinyl chloride (PVC) pipes were examined to determine if one surface type would allow better DNA recovery than the other. Ten subjects each handled components of one metal and one PVC pipe bomb. The bombs were exploded, the fragments were collected and swabbed using the double swab technique, and the samples were extracted, quantified, amplified, and genotyped using polymerase chain reaction/short tandem repeat (PCR/STR). Of the 20 bombs handled by the subjects, four bombs gave reportable results that matched the subject's known DNA profiles. An additional eight profiles, also matching the subject's known DNA profiles, were generated but were below the reportable threshold. There was no difference in the success rate of obtaining DNA profiles related to the use of either PVC or metal in the manufacture of the pipe bomb. The variables that appeared to have the greatest influence on the success of generating a DNA profile were the amount of fragmentation and subsequent recovery of the bomb fragments. It is suspected that successful DNA profiling could also be dependent upon the bomb assembler's propensity to slough skin cells on objects they handled.