THE CASCADING EFFECTS OF ADOLESCENT GANG INVOLVEMENT ACROSS THE LIFE COURSE*

The short‐run deleterious effects of gang involvement during adolescence have been well researched. However, surprisingly little empirical attention has been devoted to understanding how gang involvement in adolescence influences life chances and criminal behavior in adulthood. Drawing on the life‐course perspective, this study argues that gang involvement will lead to precocious transitions that, in turn, will have adverse consequences on the fulfillment of adulthood roles and statuses in the economic and family spheres. Moreover, problems fulfilling these conventional roles are hypothesized then to lead to sustained involvement in criminal behavior in adulthood. Using data from a sample of males from the Rochester Youth Development Study, results from structural equation models support the indirect link between gang membership and noncriminal and criminal outcomes in adulthood. Specifically, gang involvement leads to an increase in the number of precocious transitions experienced that result in both economic hardship and family problems in adulthood. These failures in the economic and family realms, in turn, contribute to involvement in street crime and/or arrest in adulthood. Implications for the criminal desistance process are discussed.     

Validation of the Seratec® SeraQuant™ for the quantitation of prostate-specific antigen levels on immunochromatographic membranes

Abstract: Use of immunochromatographic membranes for the detection of prostate‐specific antigen (PSA) has become commonplace in forensic laboratories. Experiments were designed to test the newly developed Seratec^® SeraQuant? for accuracy, precision, and consistency in the quantitation of PSA. PSA standards were diluted with buffers and run on the instruments. Values obtained were examined for accuracy (was the correct value obtained?) and precision (were multiple sample values consistent?). To test for variation between instruments, large volumes of diluted PSA standard were run repeatedly on six units and the values obtained were plotted against the known PSA values to obtain a standard curve for each instrument. Fifty membranes having negative or weak positive results were then run on the six units, and the adjusted values were recorded and compared. Results of these experiments indicate that the instruments are accurate and precise in the quantitation of low levels of PSA.     

A simulation for exploring the effects of the "trait list" method's subjectivity on consistency and accuracy of ancestry estimations

The nonmetric "trait list" methodology is widely used for estimating ancestry of skeletal remains. However, the effects of the method's embedded subjectivity on subsequent accuracy and consistency are largely unknown. We develop a mathematical simulation to test whether variation in the application of the "trait list" method alters the ancestry estimation for a given case. Our simulation explores how variations in (i) trait selection, (ii) number of traits employed, and (iii) ancestry choice thresholds affect the ancestry estimation of an unidentified skeleton. Using two temporally and geographically diverse samples, the simulation demonstrates that trait selection, trait quantity, threshold choices, and the exclusion of high-frequency traits had minimal effect on estimation of general ancestry. For all data sets and Runs, Accuracy(AS) was maintained above 90%. The authors close with a discussion on the logistical issues present when choosing traits, and how to avoid ancestry bias.     

EFFECT OF SUSPECT RACE ON OFFICERS’ ARREST DECISIONS*

Many respondents to opinion surveys say that the citizen's race influences how police officers treat the public, yet recent expert social‐science panels have declared that research findings are too contradictory to form a conclusion on whether American police are biased against racial minorities. We perform a meta‐analysis of quantitative research that estimates the effect of race on the police decision to arrest. Screening nearly 4,500 potential sources, we analyze the results based on 27 independent data sets that generated 40 research reports (both published and unpublished) that permitted an estimate of the effect size of the suspect's race on the probability of arrest. The meta‐analysis shows with strong consistency that minority suspects are more likely to be arrested than White suspects. Depending on the method of estimation, the effect size of race varied between 1.32 and 1.52. Converting the race effect size to probabilities shows that compared with the average probability in these studies of a White being arrested (.20), the average probability for a non‐White was calculated at .26. The significant race effect persists when taking into account the studies’ variations in research methods and the nature of explanatory models used in the studies. Implications for future research are presented.     

Developmental validation of feline, bovine, equine, and cervid quantitative PCR assays

Accurate DNA quantification is essential for optimizing DNA testing and minimizing sample consumption. Real-time quantitative polymerase chain reaction (qPCR) assays have been published for human and canine nuclear DNA, and the need for quantifying other forensically important species was evident. Following the strategy employed for the canine qPCR assay, we developed individual assays to accurately quantify feline, bovine, equine, and cervid nuclear DNA. Each TaqMan-based assay incorporates a genus-specific probe targeting the Melanocortin-1 Receptor gene and includes a piece of synthetic DNA that acts as an internal PCR control for detecting inhibition. Developmental validations were carried out following the revised guidelines of the Scientific Working Group on DNA Analysis Methods with modifications necessary for validation of nonhuman qPCR assays. All assays demonstrated the specificity, sensitivity, stability, reproducibility, accuracy, and precision required for forensic casework. The application of these assays to animal forensic DNA analysis has both conserved laboratory resources and improved genotyping results.     

Case series of completed suicides by burning over a 13-year period

Suicide by burning is an extreme act that is uncommon in the United States and throughout the Western world. The characteristics of people who complete such acts are not well understood. To address this issue, we examined the death records of the King County Medical Examiner's Office in Washington State over the 13 years from 1996 to 2009. Twenty-five cases of suicide by burning were identified and used to characterize decedent demographics, circumstances of death, and motivating factors. Compared to other methods of suicide, burning demonstrated a significant overrepresentation of decedents who were women, 40-59 years of age, and Asian/Pacific Islander. They also tended to have previous psychiatric illness and/or substance abuse issues. Self-burning predominantly occurred at the decedent's residence with the intent of suicide given. There was no unifying theme in motivating factors. Together, these data represent the characteristics of people whose death is because of suicide by burning in King County, Washington.     

Y-haplotype screening of local patrilineages followed by autosomal STR typing can detect likely perpetrators in some populations

The male-specific, human Y-chromosomal short tandem repeats (Y-STRs) are very useful in forensic analysis and human evolution studies. The authors report two sexual crime cases in which the perpetrators were successfully traced using Y-haplotype screening of local patrilineages followed by autosomal STR typing. First, several main local patrilineages from local cases were investigated using Y-STR haplotyping, aimed to find the pedigrees whose haplotypes were identical or similar to those of the crime scene samples. Then, several key suspects were defined from the screened pedigrees, and autosomal STR typing was performed to identify the perpetrator of the crime. The application of Y-haplotype screening of local patrilineages followed by autosomal STR typing in these two cases demonstrates its usefulness for solving sexually related crimes in certain populations.     

The dynamic character of disguise behavior for text-based, mixed, and stylized signatures

The aims of this study were to determine if dynamic parameters (duration, size, velocity, jerk, and pen pressure) differed for signing style (text-based, stylized, and mixed) and if signing style influences handwriting dynamics equally across three signature conditions (genuine, disguised, and auto-simulation). Ninety writers provided 10 genuine signatures, five disguised signatures, and five auto-simulated signatures. All 1800 signatures were collected using a digitizing tablet resulting in a database of each signature's dynamic characteristics. With genuine signatures, there were significant differences between styles for size, velocity, and pen pressure, and there were significant differences between genuine signatures and at least one of the un-natural signature conditions for all parameters. For velocity and size, these changes with condition were dependent on style. Changes with condition for the other parameters were similar for the three styles. This study shows that there are differences among natural signature styles and disguise behaviors that may be relevant in forensic signature examinations.     

Comparison of glass fragments using particle-induced X-ray emission (PIXE) spectrometry

A procedure has been developed to analyze the trace element concentrations in glass fragments using particle-induced X-ray emission (PIXE) spectrometry. This method involves using accelerated protons to excite inner-shell electronic transitions of target atoms and recording the resultant X-rays to characterize the trace element concentrations. The protocol was able to identify those glass fragments that originated from different sources based on their elemental analyses. The protocol includes specific approaches to calculating uncertainties and handling measurements below the level of detection. The results indicate that this approach has increased sensitivity for several elements with higher atomic number compared with X-ray fluorescence methods. While not as sensitive as laser-ablation or inductively coupled plasma mass spectrometry methods of dissolved samples, it is entirely nondestructive and entails a much simpler sample preparation process that may be used to presort glass fragments for more comprehensive elemental analysis. As such, the technique described may have a niche role in forensic glass analysis.