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.     

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.     

An evaluation of the Maxcan fibre finder version 3.3 on cotton fibres

The Maxcan fibre finder system is a product of Cox Analytical Systems, Sweden, and has been developed for the primary purpose of searching for fibres on tape lifts. This paper evaluates the ability of the Maxcan system to search for different fibre types and colours under varying conditions. The system performed effectively in most situations, although it did have problems with some search combinations that a human operator would also find difficult in a manual search. The Maxcan system has the added advantages of being objective, consistent and able to do large batch searches unattended. These attributes make it very useful where a large number of tapes need to be searched in casework and also in research where large quantities of data need to be gathered within a reasonable time.     

A further study to investigate the detection and enhancement of latent fingerprints using visible absorption and luminescence chemical imaging

This study investigated the application of chemical imaging to the detection of latent fingerprints using the Condor macroscopic chemical imaging system (ChemImage Corp., Pittsburgh, USA). Methods were developed and optimised for the visualisation of untreated latent fingerprints and fingerprints processed with DFO, ninhydrin, cyanoacrylate, and cyanoacrylate plus rhodamine 6G stain. The results obtained with chemical imaging were compared to the detection achieved using conventional imaging techniques. The Condor significantly improved the detection of many prints, especially those that might be considered poor quality or borderline prints. Prints on newspaper treated with ninhydrin and DFO, and prints on white and yellow paper treated with ninhydrin, benefited the most from chemical imaging detection. In many cases, fingerprints undetectable using conventional imaging techniques could be visualised with chemical imaging. Ridge detail from untreated prints on yellow paper was also detected using the Condor. When prints of high quality were examined, both detection techniques produced quality results. The results of this project demonstrate that chemical imaging offers advantages over conventional visualisation techniques when examining latent fingerprints, especially those that would be considered difficult, such as weak prints or prints on surfaces that produce highly luminescent backgrounds. Standard testing procedures for the detection and enhancement of fingerprints by chemical imaging are presented and discussed.     

Glass particles in footwear of members of the public in south-eastern Australia--a survey

A total of 776 pairs of shoes collected from random members of the public in south-eastern Australia were examined for the presence of glass fragments. From the samples collected a total of 110 fragments were recovered from 57 pairs of shoes (7.3% of the pairs examined). This study shows that the prevalence of glass fragments in footwear is dependent upon the area of the shoe from which the fragments were recovered. A much higher percentage of shoes were found to have fragments embedded in the sole (5.9%) than in the upper area of the shoe (1.9%). These shoes were also more likely to have multiple fragments from multiple sources of glass. Only a very small percentage of shoes contained fragments in both the upper and the sole (0.3%). These findings and their significance for the interpretation of glass evidence involving footwear are discussed in this study.     

The analysis of forensic samples using laser micro-pyrolysis gas chromatography mass spectrometry

Laser micropyrolysis gas chromatography-mass spectrometry is used for the analysis of paint, photocopier toner, and synthetic fiber materials to test the forensic potential of this emerging technology. It uses a laser microprobe to selectively target very small parts of the materials for GC-MS analysis. Whereas the paint and the toner samples were amenable to direct laser pyrolysis, the synthetic fibers proved transparent to the 1064 nm laser radiation. The difficulty with the fibers demonstrates that a specific laser wavelength may not be appropriate for all types of materials. Nevertheless, the fibers were able to be indirectly pyrolyzed by impregnation in a strongly absorbing graphite matrix. A vast array of hydrocarbon pyrolysates was detected from the different materials studied. Unique product distributions were detected from each sample and in sufficient detail to facilitate individual molecular characterization (i.e., molecular fingerprinting). The integrity of the laser data were confirmed by comparison to data obtained from the same samples by the more conventional pyroprobe pyrolysis GC-MS method. The high spatial resolution and selectivity of the laser method may be advantageous for specific forensic applications, however, further work may be required to improve the reproducibility of the data.