Whilst case linkage is used with serious forms of serial crime (e.g. rape and murder)

Abstract

Chemical reactions between latent fingerprints and a variety of metal surfaces are investigated by heating the metal up to temperatures of approximately 600 degrees C after deposition of the fingerprint. Ionic salts present in the fingerprint residue corrode the metal surface to produce an image of the fingerprint that is both durable and resistant to cleaning of the metal. The degree of fingerprint enhancement appears independent of the elapsed time between deposition and heating but is very dependent on both the composition of the metal and the level of salt secretion by the fingerprint donor. Results are presented that show practical applications for the enhancement to fingerprints deposited in arson crime scenes, contaminated by spray painting, or deposited on brass cartridge cases prior to discharge. The corrosion of the metal surface is further exploited by the demonstration of a novel technique for fingerprint enhancement based on the electrostatic charging of the metal and then the preferential adherence of a metallic powder to the corroded part of the metal surface.

In the absence of forensic evidence (such as DNA or fingerprints), offender behavior can be used to identify crimes that have been committed by the same person (referred to as behavioral case linkage). The current study presents the first empirical test of whether it is possible to link different types of crime using simple aspects of offender behavior. The discrimination accuracy of the kilometer-distance between offense locations (the intercrime distance) and the number of days between offenses (temporal proximity) was examined across a range of crimes, including violent, sexual and property-related offenses. Both the intercrime distance and temporal proximity were able to achieve statistically significant levels of discrimination accuracy that were comparable across and within crime types and categories. The theoretical and practical implications of these findings are discussed and recommendations made for future research. Keywords ProximityOne of the most compelling and well-supported findings in criminology is that the majority of crime is committed by a minority of offenders (e.g. Kershaw, Nicholas, & Walker, 2008;Laub, 2004;Piquero, Farrington, & Blumstein, 2007). In the United States (US), for example, estimates suggest that approximately 5% of offenders are responsible for 30% of felony convictions (Office of the Legislative Auditor, 2001). Findings such as these suggest that an effective way for the police to tackle and reduce crime is to target serial and repeat offenders who are responsible for a disproportionate amount of crime.Targeting serial offenders specifically, however, requires the police to identify serial offenses (referred to hereafter as linked crime series), which are essentially two or more crimes committed by the same offender or the same group of offenders (Woodhams, Hollin, & Bull, 2007). The most reliable way of identifying linked crime series is through the recovery of forensic evidence, such as DNA or fingerprints, left at the scenes of several different crimes (Grubin, Kelly, & Brunsdon, 2001). However, despite the impression that television programs such as CSI create, the availability of forensic evidence is surprisingly limited, with less than 1% of recorded crimes yielding such evidence (House of Commons, 2005). Therefore, the police often need to rely on other approaches to linking crime. One potential alternative is to use behavioral similarity, whereby crimes that show evidence of similar offender behavior are judged to have been committed by the same offender/s (referred to as linked crimes), whereas those that involve different behavior are said to have been committed by different offenders Running head: Linking Different Types of Crime 3 (referred to as unlinked crimes). This procedure is known by several names, including linkage analysis and comparative case analysis, but the term behavioral case linkage will be used in the current paper. Behavioral Case LinkageBehavioral case linkage is an investigative procedure that has received growing attention both prac...

DNA material is now collected routinely from crime scenes for a wide range of offences and the timely processing of the DNA is seen as key to its success in investigating and detecting crime. An analysis of DNA material recovered from the volume crime offences of residential burglary, commercial burglary, and theft of motor vehicle in Northamptonshire, U.K., in 2004 has enabled the DNA to be categorized into seven sources. Further analysis using a logistical regression has revealed a number of predictors, other than timeliness, that greatly influence whether the DNA material recovered from a crime scene enables the crime to be detected. The results indicate that a number of these predictors are of statistical significance and may be just as relevant in determining whether DNA successfully detects the crime as the timeliness of the processing of the DNA material. The most significant predictor was found to be investigating officer accreditation with location, quantity, and type of DNA material at the crime scene also being relevant. Accreditation of the Crime Scene Examiner recovering the DNA material was found not to be significant. Consideration is given to where further emphasis is needed by the U.K. police service to maximize the opportunities to detect volume crime with DNA.

Much previous research on behavioural case linkage has used binary logistic regression to build predictive models that can discriminate between linked and unlinked offences. However, classification tree analysis has recently been proposed as a potential alternative owing to its ability to build user‐friendly and transparent predictive models. Building on previous research, the current study compares the relative ability of logistic regression analysis and classification tree analysis to construct predictive models for the purposes of case linkage. Two samples are utilised in this study: a sample of 376 serial car thefts committed in the UK and a sample of 160 serial residential burglaries committed in Finland. In both datasets, logistic regression and classification tree models achieve comparable levels of discrimination accuracy, but the classification tree models demonstrate problems in terms of reliability or usability that the logistic regression models do not. These findings suggest that future research is needed before classification tree analysis can be considered a viable alternative to logistic regression in behavioural case linkage. Copyright © 2012 John Wiley & Sons, Ltd.

Apparatus constructed to measure the variation (ΔV) in applied potential (V) over the surface of brass discs subject to corrosion by latent finger mark deposits is described. Results show values of ΔV of up to 14 V for V = 1400 V on regions of disc coincident with the location of finger mark corrosion. Measurement of ΔV for 0 V ⩽ V ⩽ 1400 V has revealed a non-linear relationship, which is very similar to that measured for a commercial metal–semiconductor Schottky rectifier. Further experiments have shown the corrosion product on the brass to be a p-type semiconductor with current/voltage characteristics for the brass-corrosion contact consistent with the characteristics expected for a rectifying metal–semiconductor contact. The composition of the semiconductor is discussed in terms of metal oxide corrosion products with p-type copper (I) and copper (II) oxides thought most likely to be responsible for the semiconductor behaviour of the corrosion product. A simple model is described for the galvanic corrosion of brass by finger mark deposits that is consistent with the experimental results.

Journey to crime studies have attempted to illuminate aspects of offender decision making that have implications for theory and practice. This article argues that our current understanding of journey to crime is incomplete. It improves our understanding by resolving a fundamental unit of analysis issue that had thus far not received much attention in the literature. It is demonstrated that the aggregate distribution of crime trips (commonly known as the distance decay) does not take into account the considerable variation that exists between individual offenders' crime trip distributions. Moreover, the common assumption of statistical independence between observations that make up a distribution is something that, until now, has yet to be tested for distributions of crime trips of multiple offenders. In order to explore these issues, three years of burglary data from a UK police force were linked to 32 prolific offenders to generate journey to crime distributions at the aggregate and offender levels. Using multi-level models, it was demonstrated that the bulk (65%) of the variation of journeys to crime exists at the offender level, indicating that individual crime trips are not statistically independent. In addition the distance decay pattern found at the aggregate level was not, in the main, observed at the offender level-a result that runs counter to conventional wisdom, and another example of the ecological fallacy. The implications of these findings are discussed.