High Resolution Imaging of Latent Fingerprints by Localized Corrosion on Brass Surfaces

Abstract:  The Atomic Force Microscope (AFM) is capable of imaging fingerprint ridges on polished brass substrates at an unprecedented level of detail. While exposure to elevated humidity at ambient or slightly raised temperatures does not change the image appreciably, subsequent brief heating in a flame results in complete loss of the sweat deposit and the appearance of pits and trenches. Localized elemental analysis (using EDAX, coupled with SEM imaging) shows the presence of the constituents of salt in the initial deposits. Together with water and atmospheric oxygen—and with thermal enhancement—these are capable of driving a surface corrosion process. This process is sufficiently localized that it has the potential to generate a durable negative topographical image of the fingerprint. AFM examination of surface regions between ridges revealed small deposits (probably microscopic "spatter" of sweat components or transferred particulates) that may ultimately limit the level of ridge detail analysis.     

A Comparison of Cleaning Regimes for the Effective Removal of Fingerprint Deposits from Brass

Abstract:  Effective removal of fingerprint deposits is crucial for experimentation related to the corrosion of metals by fingerprint deposits. Such removal is also necessary prior to deposition of test fingerprints. The effectiveness of four regimes in removing fingerprint deposits from brass is considered. Sustained wiping of the deposit with a tissue at applied pressures of up to c . 1430 Pa or rubbing while the brass was immersed in acetone both failed to remove completely all traces of fingerprint deposits. Heating the brass to 600°C was an effective remover; however, this also oxidized the surface of the metal except where inhibited by fingerprint deposits. The most effective regime, and the only one of the four that removed all traces of deposit without affecting the properties of the metal surface, was immersion in warm soapy water while rubbing with a tissue. We propose this as the preferred method for fingerprint removal.     

A Statistical Validation of the Individuality and Repeatability of Striated Tool Marks: Screwdrivers and Tongue and Groove Pliers*

Abstract: Tool mark identification relies on the premise that microscopic imperfections on a tool’s working surface are sufficiently unique and faithfully transferred to enable a one‐to‐one association between a tool and the tool marks it creates. This paper presents a study undertaken to assess the validity of this premise. As part of this study sets of striated tool marks were created under different conditions and on different media. The topography of these tool marks was acquired and the degree of similarity between them was quantified using well‐defined metrics. An analysis of the resulting matching and nonmatching similarity distributions shows nearly error‐free identification under most conditions. These results provide substantial support for the validity of the premise of tool mark identification. Because the approach taken in this study relies on a quantifiable similarity metric, the results have greater repeatability and objectivity than those obtained using less precise measures of similarity.     

Quick Screening of Crystal Methamphetamine/Methyl Sulfone Exhibits by Raman Spectroscopy

Abstract: The analysis of mixtures of “crystal meth” (usually comprised of methyl sulfone [MS] and methamphetamine [MA]) by gas chromatography‐mass spectrometry (GCMS) is routine in many forensic drug laboratories. The utilization of Raman spectroscopy for the identification of such mixtures quickly and without the need for a separation technique is discussed. Samples were dissolved in water and Raman spectra of the resulting aqueous solutions were collected. By comparing these spectra to spectra of methylsulfone and MA mixtures of known composition, an indication of the composition of the sample can be obtained in only a few minutes. This spectral comparison also can be used as a semi‐quantitative analysis of MA concentrations in such exhibits.     

Criminal career progression among serious youthful offenders in Australia

An important question from research on criminal careers is whether the processes that generate participation in criminal activity are similar to those that drive offending frequency among those who have initiated. This article considers basic demographic correlates asking whether those factors are associated with both initial and sustained early adulthood criminality in Australia. Three findings emerged from the study: (1) the offenders exhibited high levels of criminal activity during early adulthood; (2) males were more likely than females to offend and offend at higher rates as adults; and (3) Indigenous youth were more likely than non-Indigenous youth to offend and offend at higher rates as adults. Overall, the study results showed that basic correlates of crime were linked to both participation and frequency of offending in early adulthood—even within a sample of serious offenders. The article addresses the theoretical implications of the findings and directions for future research.     

Informal Controls and the Explanation of Propensity to Offend: A Test in Two Urban Samples

Propensity to offend is an important and stable predictor of offending. A person’s propensity is often thought of as a multidimensional trait consisting of morality and low self-control. The aim of this paper is to explain individual differences in propensity to offend as one single construct and two of its dimensions, namely morality and low self-control. It is well established that low levels of morality and low self-control increase the risk of offending. However, there is less empirical research that focuses on the main predictors of morality and self-control. Therefore the main research question for this study is to explain to what extent parental attachment, parental control and the school social bond have a direct effect on one’s propensity to offend (low morality or delinquency tolerance and low self-control). The data are drawn from two different samples of young adolescents in Antwerp, Belgium (N = 2,486), and Halmstad, Sweden (N = 1,003). The results show that parental control, parental attachment and the school social bond have direct effects on individual differences in propensity to offend, regardless of individual background variables. The results are highly equivalent in both samples. The similarity of the results across two independent samples suggests that the findings are stable. Implications for further studies are discussed.     

Neuropsychological Tests are Poor at Assessing the Frontal Lobes, Executive Functions, and Neurobehavioral Symptoms of Traumatically Brain-Injured Patients

The frontal lobes play a major role in the regulation of our emotions and behavior, planning, decision making, social conduct, actions, and executive functions. They are quite vulnerable to damage when an individual sustains a moderate or severe traumatic brain injury. Patients who sustain damage to their frontal lobes may not complain of any cognitive or neurobehavioral symptoms. They often do not show any abnormalities on standardized neuropsychological tests, particularly when the anterior and ventral areas of their frontal lobes are damaged. When these patients are observed in unstructured, novel, or complex real-world settings, they frequently exhibit cognitive difficulties, neurobehavioral symptoms, and problems with their executive functions. Since standardized neuropsychological tests are generally poor at assessing these problems and symptoms, neuropsychologists may not be aware of these problems if they have never observed these patients function in real-world settings or have never interviewed the significant others of these patients. As a consequence, neuropsychologists should not rely solely on the quantitative test data of these patients since it may provide inaccurate and misleading information.