Evaluation of sieving polymers for fast, reproducible electrophoretic analysis of short tandem repeats (STR) in capillaries

Efficient capillary electrophoretic STR analysis requires rapid, reproducible and robust separation of DNA fragments with reasonable capillary longevity--this is currently accomplished using proprietary commercial polymeric sieving matrices specifically developed for this separation. These matrices, while effective, are costly and do not provide adequate resolution of STR DNA fragments in capillaries with shorter effective separation lengths, increasing the time required to accomplish the separation and minimizing the potential extrapolation to other miniaturized platforms. As the forensic community looks toward next generation microchip technology as a means of processing casework more rapidly, new sieving polymers need to be evaluated for utilization in this platform. The research presented here describes the assessment of commercially-available polymeric sieving matrices for STR analysis, with consideration given to feasibility of incorporation into a microdevice. Polymer composition, molecular weight, and concentration were evaluated, along with an assessment of the effects of buffer composition, separation temperature, and capillary length. These variables were evaluated individually or collectively on the ability to resolve STR DNA fragments and the reproducibility of the separations and the results compared to a proprietary commercial product. A 600,000 Da MW poly(ethylene oxide) (PEO) solution at a 3% (w/v) concentration was determined to be the most suitable matrix for these separations. This polymer, in coated capillaries, provided highly robust and reproducible separations, with near baseline resolution of fragments having single base differences. Reductions in the temperature of the separation, from 60 degrees C to 40 degrees C, and the urea concentration of the buffer, from 7 M to 3.5 M, provided increased longevity of the PEO polymer for repeated separations. Comparison of this polymer with currently specified commercial products used for STR analysis showed that the optimized PEO matrix provided superior separations under all conditions tested. In addition, PEO could be utilized in shorter capillary systems, with a concurrent decrease in analysis time, highlighting its potential for use in shortened capillary or microdevice systems.     

A coffee can, factor analysis, and prediction of antisocial behavior: the structure of criminal risk

The predictive accuracy of the Psychopathy Checklist-Revised, Level of Service Inventory-Revised, Violence Risk Appraisal Guide, and the General Statistical Information on Recidivism were compared to four instruments randomly generated from the total pool of original items. None of the four original instruments better predicted post-release failure than the four randomly generated instruments. These results suggest two conclusions: (a) the instruments are only measuring criminal risk, and (b) no single instrument has captured sufficient risk assessment theory to result in better prediction than randomly derived instruments measuring criminal risk. A two-stage factor analysis was completed on 1614 cases. This analysis of the risk items indicated a 4-factor solution and all 4 factors were equal to the original instruments in predicting post-release failure. Thus, the original instruments did not improve prediction over randomly structured scales, nor did the restructuring of items improve risk assessment, suggesting substantial deficiencies in the conceptualization of risk assessment and instrumentation. We argue that developing a risk-based construct, which involves hypothesis testing and an explanation of behavior, is the optimal method to advance risk assessment within the criminal justice and mental health systems. Such an approach would provide targeted areas for clinical intervention that are salient to risk.     

Proficiency testing (external quality assessment) of drug detection in oral fluid

Eighteen external quality assessment (proficiency testing) samples were prepared from client specimens collected with the Intercept oral fluid collection device and by spiking drug-free oral fluid. Samples were circulated in pairs at quarterly intervals to 13 UK and USA based laboratories for analysis by a panel of OraSure micro-plate Intercept enzyme immunoassay kits and hyphenated mass spectrophotometric techniques. During the survey, there was a single case of non-specificity in a false report for methadone. The major errors were of lack of sensitivity relative to the concentration thresholds specified for the immunoassays. The sensitivity for overall "present"/"not found" reports calculated as true positives/(true positives+false negatives) were for the amphetamine specific assay 50%, methyl-amphetamines 93%, barbiturates 64%, cannabinoids 73%, cocaine and metabolites 100%, benzodiazepines 69%, methadone 95%, opiates 79% (opiates excluding oxycodone 93%), phencyclidine 93% and human gamma-globulin 97%. A small number of the sensitivity errors were attributable to errors in chromatographic confirmation techniques.     

Mandarins and kibitzers:men in and around the trenches of political power in Ottawa*

Book reviewed in this article: My Life and Work, A Happy Partnership: Memoirs of J. A. Corry. A Man of Influence: Norman A. Robertson and Canadian Statecraft, 1929–1968. The Ottawa Men: The Civil Service Mandarins 1935–1957.     

Differentiation of black gel inks using optical and chemical techniques

Gel ink pens have become a common writing instrument in the United States. Questioned document examiners often attempt to optically differentiate gel inks from each other and from other non-ballpoint ink writings (e.g., those from roller-ball pens). Since early formulations were primarily pigment-based, they do not elute when analyzed by thin-layer chromatography. However, recent gel ink formulations (i.e., within the past five years) include dye-based inks that can be easily separated. This study differentiates black gel inks using optical and chemical techniques. The techniques include: microscopy, visible and near infrared reflectance, near infrared luminescence, thin-layer chromatography (TLC), spot tests, and gas chromatography/mass spectrometry (GC/MS). As a result of this study a flow chart has been developed allowing for a systematic determination of a questioned ink. In addition, an analysis of volatile compounds found in gel inks revealed that there are some unique ingredients that may be found in gel inks that are not typically found in other non-ballpoint inks.     

From animal cruelty to serial murder: applying the graduation hypothesis

Although serial murder has been recorded for centuries, limited academic attention has been given to this important topic. Scholars have attempted to examine the causality and motivations behind the rare phenomenon of serial murder. However, scant research exists which delves into the childhood characteristics of serial murderers. Using social learning theory, some of these studies present supporting evidence for a link between childhood animal cruelty and adult aggression toward humans. Based on five case studies of serial murderers, we contribute to the existing literature by exploring the possible link between childhood cruelty toward animals and serial murder with the application of the graduation hypothesis.     

The forensic analysis of thermal transfer printing

Thermal transfer printing refers to printing processes that utilize heat to produce an image by either physical or chemical means or by a combination of both. As the technology has improved and the supplies have become less expensive, the use of thermal printing in the personal and business markets has increased significantly. Specifically, dye diffusion thermal transfer and thermal mass transfer have become predominant in the production of counterfeit credit cards, drivers' licenses, and other types of documents produced on plastic media. Chemical analysis by means of thin layer chromatography (TLC) has proven to be useful in characterizing various types of inks (e.g., writing and inkjet inks). In this study, the authors examined 81 different samples that included a total of 54 printer samples (43 photographic prints on paper and eleven plastic card samples) and 27 printer ribbons. A new TLC method was developed and tested utilizing a solvent system (80% n-hexane, 3% methyl ethyl ketone, and 17% ethyl acetate) that is capable of producing excellent resolution.