Forensic Analysis of Explosives Using Isotope Ratio Mass Spectrometry (IRMS)—Part 2: Forensic Inter-Laboratory Trial: Bulk Carbon and Nitrogen Stable Isotopes in a Range of Chemical Compounds (Australia and New Zealand)

Abstract:  Comparability of data over time and between laboratories is a key issue for consideration in the development of global databases, and more broadly for quality assurance in general. One mechanism that can be utilized for evaluating traceability is an inter-laboratory trial. This paper addresses an inter-laboratory trial conducted across a number of Australian and New Zealand isotope ratio mass spectrometry (IRMS) laboratories. The main objective of this trial was to determine whether IRMS laboratories in these countries would record comparable values for the distributed samples. Four carbon containing and four nitrogen containing compounds were distributed to seven laboratories in Australia and one in New Zealand. The laboratories were requested to analyze the samples using their standard procedures. The data from each laboratory was evaluated collectively using International Standard ISO 13528 ( Statistical methods for use in proficiency testing by inter-laboratory comparisons ). "Warning signals" were raised against one participant in this trial. "Action signals" requiring corrective action were raised against four participants. These participants reviewed the data and possible sources for the discrepancies. This inter-laboratory trial was successful in providing an initial snapshot of the potential for traceability between the participating laboratories. The statistical methods described in this article could be used as a model for others needing to evaluate stable isotope results derived from multiple laboratories, e.g., inter-laboratory trials/proficiency testing. Ongoing trials will be conducted to improve traceability across the Australian and New Zealand IRMS community.     

Functional Neuroimaging of Symptom Validity Testing in Traumatic Brain Injury

The Word Memory Test (WMT) is a commonly used symptom validity test (SVT) that assesses recognition verbal memory. The task has been adapted for use within a functional magnetic resonance imaging (fMRI) paradigm so the neural correlates of WMT activation patterns can be studied. In the current investigation, performance on the delayed recognition subtest of the WMT was examined in two patients who sustained severe TBI and compared to ten healthy controls. The patients underwent comprehensive neuropsychological evaluations and structural MRI. All participants completed two versions of the WMT: full-effort and simulated poor effort conditions. Despite extensive structural brain damage, the fMRI activation patterns during full-effort WMT performance were somewhat similar in the two TBI patients and likewise, somewhat similar to controls. The fMRI activation pattern in both patients demonstrated intact activation of the basic neural structures necessary to perform the WMT. Dissimilar patterns of activation were obtained during the simulated poor effort condition of WMT performance suggesting that fMRI techniques may be sensitive in demonstrating non-credible cognitive performance. The results of our study represent the first fMRI investigation of normal and simulated poor effort SVT performance in individuals with documented brain damage. The implications of fMRI techniques in SVT research and their clinical application are discussed.     

A comparison of memory for homicide, non-homicidal violence, and positive life experiences

Defendants commonly claim amnesia for their criminal actions especially in cases involving extreme violence. While some claims are malingered or result from physiological factors, other cases may represent genuine partial or complete amnesia resulting from the psychological distress and/or extreme emotion associated with the perpetration of the crime. Fifty Canadian homicide offenders described their memories of their homicide, a non-homicide violent offense, and their most positive adulthood life experience. Self-reported and objective measures of memories for these events revealed that homicides were recalled with the greatest level of detail and sensory information. Although dissociative tendencies were associated with a self-reported memory loss, objective measures of memory quality did not reflect this perceived impairment, suggesting a failure of meta-memory. Recollections of positive life events were superior to those of non-homicidal violence, possibly due to greater impact and meaning attached to such experiences. Findings suggest that memory for homicide typically is enhanced by the powerful emotion associated with its perpetration.     

The Recovery of Latent Fingermarks from Evidence Exposed to Ionizing Radiation*

Abstract: Continual reports of illicit trafficking incidents involving radioactive materials have prompted authorities to consider the likelihood of forensic evidence being exposed to radiation. In this study, we investigated the ability to recover latent fingermark evidence from a variety of substrates that were exposed to ionizing radiation. Fingermarks deposited on common surfaces, including aluminum, glass, office paper, and plastic, were exposed to doses ranging from 1 to 1000 kGy, in an effort to simulate realistic situations where evidence is exposed to significant doses of radiation from sources used in a criminal act. The fingermarks were processed using routine fingermark detection techniques. With the exception of glass and aluminum substrates, radiolysis had a considerable effect on the quality of the developed fingermarks. The damage to ridge characteristics can, in part, be attributed to chemical interactions between the substrate and the components of the fingermark secretions that react with the detection reagents.     

The Juvenile Justice Reform Act of 2018: Updating the Federal Approach to Youth Involved,and At‐Risk of Becoming Involved,in the Juvenile Justice System

On December 21, 2018, the Juvenile Justice Reform Act was signed into law, marking the first update in 16 years to the Juvenile Justice and Delinquency Prevention Act of 1974, as amended. The reforms reflect much of the knowledge that has been gained through research and science over the past decade and strengthen the Act’s core protections for youth in the juvenile justice system. The changes also expand the Office of Juvenile Justice and Delinquency Prevention’s role in research, and technical assistance, and provide for additional oversight for related programs.     

Evaluation of iodine-benzoflavone and ruthenium tetroxide spray reagents for the detection of latent fingermarks at the crime scene

The performance of two spray reagents, iodine-benzoflavone and ruthenium tetroxide (RTX), was evaluated and compared with the conventional technique currently used at the crime scene, that is, powdering. Neither the spray techniques nor powdering were shown to be suitable for all surfaces and ages of marks tested. On some surfaces such as glass and treated wood, powdering was still the superior technique, whereas the spray techniques produced better development on wallpaper, vinyl, and brick. Sequencing work showed that RTX was incompatible with powdering and cyanoacrylate (with a rhodamine 6G stain). Iodine-benzoflavone can be used successfully either before or after powdering in a sequence; however, it was incompatible with cyanoacrylate. Two non-CFC formulations of iodine-benzoflavone using HFC4310mee and HFE7100 solvents were tested and shown not to be as effective as the original Arklone (CFC-113) formulation; however, the HFC4310mee solvent is recommended as the most suitable replacement solvent. Due to the expense of the commercial RTX spray, attempts at formulating a more cost-effective version were also carried out. A formulation was developed that gave comparable development to the commercial version but at a much cheaper cost, and with a shelf life of up to two months. Recommendations are presented for which techniques are suitable for different surfaces and ages of marks. Powdering was shown to be the best technique on all ages of marks tested on treated wood, glass, and also on marks aged three days and older on paint. Iodine-benzoflavone was the best technique on wallpaper, vinyl, brick, and raw wood. RTX was the best detection technique for fresh marks and marks aged up to one day on wallpaper and paint.     

Forensic applications of chemical imaging: latent fingerprint detection using visible absorption and luminescence

Chemical imaging technology is a rapid examination technique that combines molecular spectroscopy and digital imaging, providing information on morphology, composition, structure, and concentration of a material. Among many other applications, chemical imaging offers an array of novel analytical testing methods, which limits sample preparation and provides high-quality imaging data essential in the detection of latent fingerprints. Luminescence chemical imaging and visible absorbance chemical imaging have been successfully applied to ninhydrin, DFO, cyanoacrylate, and luminescent dye-treated latent fingerprints, demonstrating the potential of this technology to aid forensic investigations. In addition, visible absorption chemical imaging has been applied successfully to visualize untreated latent fingerprints.