Linking Personal Robbery Offences Using Offender Behaviour

Abstract

Case linkage uses crime scene behaviours to identify series of crimes committed by the same offender. This paper tests the underlying assumptions of case linkage (behavioural consistency and behavioural distinctiveness) by comparing the behavioural similarity of linked pairs of offences (i.e. two offences committed by the same offender) with the behavioural similarity of unlinked pairs of offences (i.e. two offences committed by different offenders). It is hypothesised that linked pairs will be more behaviourally similar than unlinked pairs thereby providing evidence for the two assumptions. The current research uses logistic regression and receiver operating characteristic analyses to explore which behaviours can be used to reliably link personal robbery offences using a sample of 166 solved offences committed by 83 offenders. The method of generating unlinked pairs is then refined to reflect how the police work at a local level, and the success of predictive factors re‐tested. Both phases of the research provide evidence of behavioural consistency and behavioural distinctiveness with linked pairs displaying more similarity than unlinked pairs across a range of behavioural domains. Inter‐crime distance and target selection emerge as the most useful linkage factors with promising results also found for temporal proximity and control. No evidence was found to indicate that the property stolen is useful for linkage. Copyright © 2012 John Wiley & Sons, Ltd.

Linking Crimes Using Behavioural Clues: Current Levels of Linking Accuracy and Strategies for Moving Forward

“…Likewise, a great deal of variability in reported AUCs is evident across studies, with some AUCs being very low (e.g. AUC = 0.45 in Burrell, Bull, & Bond, ) and some being extremely high (e.g. AUC = 0.96 in Melnyk, Bennell, Gauthier, & Gauthier, ).…”

“…The lowest AUC obtained in the studies (0.45) involved a study of personal robbery by Burrell et al . () when they examined the predictive accuracy of variables related to property stolen.…”

“…(), and Tonkin, Santtila, and Bull () (interestingly, levels of linking accuracy in Finnish burglaries appear to be substantially higher; Tonkin, Santtila et al ., ). The AUC ranges in studies of car theft are also very wide (0.54–0.93 in Davies et al ., ; 0.56–0.81 in Tonkin et al ., ; and 0.50–0.82 in Tonkin, Woodhams, Bull, Bond, & Santtila, ), as is the range in the lone study of personal robbery (0.45–0.92; Burrell et al ., ).…”

“…The most consistent finding is that inter‐crime distance and temporal proximity are associated with some of the largest AUC values, and these values often exceed the AUCs associated with more common MO behaviours (such as the type of home that was targeted in a burglary or what property was stolen; Bennell & Canter, ; Bennell & Jones, ; Markson et al ., ; Tonkin, Santtila et al ., ; Tonkin, Woodhams, Bull, Bond, & Santtila, ). As Tonkin (forthcoming) has noted, similar findings have also been observed with car theft (Davies et al ., ; Tonkin et al ., ) and personal robbery (Burrell et al ., ), but research examining the potential value of spatial and temporal variables in cases of sexual assault/rape and homicide is lacking. One of the reasons for this is that, for linking studies involving interpersonal crimes to have sufficiently large samples, the crimes would need to be much more geographically and temporally dispersed than for studies of high‐volume property crimes.…”

Behavioral Consistency Among Serial Burglars

“…But if a group of related behaviors is taken together, then the dominant theme of the behaviors will supersede and will not be influenced by variations in a few characteristics (Grubin et al, 1997;Woodhams & Toye, 2007). It also means that analyzing a multivariate profile of offending behaviors, rather than each individual crime scene behavior, is the most promising method of determining specialization in crime scene behaviors across multiple offenses (Burrell, Bull, & Bond, 2012;Grubin et al, 2001;Markson et al, 2010;Santtila et al, 2005;Santtila, Runtti, & Mokros, 2004;Woodhams, Grant, & Price, 2007). Davies, 1992;Markson et al, 2010;Sorochinski & Salfati, 2010).…”