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Investigating Offending Consistency of Geographic and Environmental Factors Among Serial Sex Offenders A Comparison of Multiple Analytical Strategies

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Abstract

Crime linkage analysis constitutes a tool to help investigators prioritize suspects, but a scarcity of research and methodological issues limits our knowledge on behavioral consistency in sexual offenses. The current study identifies geographic and environmental factors that are useful in examining offending consistency across series of sexual assaults using different specialization coefficients. The current study draws on criminal career research and methodology as a way to improve the study of behavioral consistency. The sample includes 72 serial stranger sex offenders who have committed a total of 361 sexual assaults. Three methods are used (i.e., diversity index, forward specialization coefficient, and Jaccard’s coefficient) and reveal a high degree of offending consistency. All three methods also highlight promising factors to rely on for crime linkage of serial sexual offenses. Empirical and methodological implications for behavioral consistency research are discussed as well as practical implications for police investigations and crime linkage.

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... Given the predictability and patterned nature of the crime, research finds that stranger serial rapists tend to be fairly consistent across offenses, including their behavior and site selection [9,10]. For example, a recent study on the spatial proximity of rapes in a series for a large sample of serial rapists in the UK found that a majority of serial rapists committed rapes that were close in proximity (12 km). ...
... Criminal recidivism most often implies repeated adjudication in the criminal justice system [9], meaning that the offender is connected to two or more separate crimes via arrest and/or conviction [12], i.e., being "caught" once and then being "caught" at least one more time. The most recent national sexual recidivism rates find that approximately 8% of the released prisoners who had been convicted of a sexual offense were arrested for a subsequent sexually-based offense within those nine years [25]. ...
... Empirical evidence suggests that stranger serial rapists tend to have a great degree of behavioral consistency across offenses [9,[28][29][30]. However, as these studies point out, much of the earlier literature on rape crime linkage (behavioral consistency and distinctiveness) was based on small samples of rapes where the offender's modus operandi or MO was consistent and distinctive enough to be linked and result in a conviction ("solved"). ...
Article
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Environmental criminological research on rape series is an understudied field due largely to deficiencies in official and publicly available data. Additionally, little is known about the spatial patterns of rapists with a large number of stranger rapes. With a unique integration and application of spatial, temporal, behavioral, forensic, investigative, and personal history data, we explore the geography of rape of a prolific, mobile serial stranger rapist identified through initiatives to address thousands of previously untested rape kits in two U.S. urban, neighboring jurisdictions. Rape kit data provide the opportunity for a more complete and comprehensive understanding of stranger rape series by linking crimes that likely never would have been linked if not for the DNA evidence. This study fills a knowledge gap by exploring the spatial offending patterns of extremely prolific serial stranger rapists. Through the lens of routine activities theory, we explore the motivated offender, the lack of capable guardianship (e.g., built environment), and the targeted victims. The findings have important implications for gaining practical and useful insight into rapists’ use of space and behavioral decision-making processes, effective public health interventions and prevention approaches, and urban planning strategies in communities subjected to repeat targeting by violent offenders.
... The thrust of much literature is on the profiling of different types of serial sex offenders for its probative value-usually to associate multiple crimes to an individual through crime linkage or predicting the behaviors of at-large offenders (Beauregard et al., 2007;Corovic et al., 2012;Deslauriers-Varin & Beauregard, 2013;Hewitt & Beauregard, 2014;Hewitt, Beauregard, & Davies, 2012;Kocsis, Cooksey, & Irwin, 2002;Park et al., 2008;Slater et al., 2014;Warren et al., 1999;Woodhams, Hollin, & Bull, 2007). A more selective approach bases profiles on geographic analysis (Beauregard et al., 2007;Canter & Larkin, 1993;Lundrigan & Czarnomski, 2006;Meaney, 2004;Strangeland, 2005) where the authors ground their findings in the context of their own geographic locales (i.e., patterns observed in the USA are similar but not exactly the same as those observed in South Africa), but still reveals a level of consistency not generally found in other aspects of a "traditional" offending pattern, particularly in regard to "hunting grounds," release sites, and distance from an offender's home or work address. ...
... A recent line of inquiry involves understanding the environmental similarities of offense sites. Analysis reveals that this component of offending may remain more stable than other variables (Deslauriers-Varin & Beauregard, 2013). All of these studies assume that at least some aspects of a perpetrator's offending pattern remain stable enough across incidents to distinguish crimes committed by that individual from similar crimes committed by others, such as the level of sexual intrusiveness, the presence or type of weapon used, or even whether a trajectory pattern can be detected (cf. ...
... In other words, offending patterns seem to be driven to a large extent by the victim-offender relationship more so than maintaining a consistent offending pattern, as the former sets the stage for how the offense occurs. Previous research on serial sex offenders supports this assumption but also finds that the victim-offender relationship is complicated by other factors such as the age of the victim and situational, environmental, and geographic factors (Beauregard, Leclerc, & Lussier, 2012;Deslauriers-Varin & Beauregard, 2013. Future research should explore the extent to which these findings apply to serial sex offenders identified via the DNA testing of unsubmitted SAKs. ...
Article
Purpose Much of what we know about serial sex offenders is based on multiple sexual assaults linked via conviction or self-report or offenders who primarily target strangers. Our data are derived from serial sex offenders linked via DNA testing of unsubmitted sexual assault kits—which provides a more objective examination of offending patterns. Methods Study uses descriptive statistics, chi-square tests, and sexual assault narratives to explore offending patterns for serial vs. nonserial sex offenders and crossover offending patterns by relationship, age, and gender for serial sex offenders. We examine crossover offending patterns for three groups of serial sex offenders: those who assaulted only strangers, both strangers and nonstrangers, and only nonstrangers. Results Findings show significant crossover offending by relationship and age. Over one-quarter sexually assaulted both strangers and nonstrangers. Serial sex offenders often vary their offending pattern across offenses. The offender-victim relationship appears particularly salient when assessing offending patterns. Conclusions Offending patterns are not a consistently reliable link across assaults. Many of these sexual assaults had not been linked prior to DNA testing, thereby illustrating the power of the DNA testing of SAKs for identifying and linking serial sex offenders, particularly when testing is followed by a thorough investigation.
... In the absence of the three most effective means of identifying offendersforensic evidence, eyewitnesses, and offender confessions-suspect prioritization through the use of behavioral information present at a crime scene becomes a valuable tool to help police identify or narrow down the range of potential suspects in unsolved cases (Deslauriers-Varin & Beauregard, 2013). While the practice of offender profiling involves the more general use of behavioral and psychological crime scene information for suspect prioritization in law enforcement investigations (see, for example, Douglas, Ressler, Burgess, & Hartman, 1986), the sub-field of crime linkage analysis (CLA) refers to the process of linking a known offender to one or more unsolved crimes based on high levels of consistency and distinctiveness in crime scene behaviors across a series of offenses (Deslauriers-Varin & Beauregard, 2013). ...
... In the absence of the three most effective means of identifying offendersforensic evidence, eyewitnesses, and offender confessions-suspect prioritization through the use of behavioral information present at a crime scene becomes a valuable tool to help police identify or narrow down the range of potential suspects in unsolved cases (Deslauriers-Varin & Beauregard, 2013). While the practice of offender profiling involves the more general use of behavioral and psychological crime scene information for suspect prioritization in law enforcement investigations (see, for example, Douglas, Ressler, Burgess, & Hartman, 1986), the sub-field of crime linkage analysis (CLA) refers to the process of linking a known offender to one or more unsolved crimes based on high levels of consistency and distinctiveness in crime scene behaviors across a series of offenses (Deslauriers-Varin & Beauregard, 2013). Unlike other practices in offender profiling, which tend to take a more clinical approach to evaluating offenders and their crime scene behavior (Copson, Badcock, Boon, & Britton, 1997), CLA relies on the statistical analysis of police data to uncover patterns in offending, and links an unsolved crime to another behaviorally similar cases in which the responsible offender is usually already known (Woodhams, Hollin, & Bull, 2007). ...
... Although some variation has been found in the type and level of behavioral consistency shown by different types of offenders, and when using different analytical methods, research on CLA has been fairly successful in identifying solved and unsolved cases committed by the same offender. Specifically, behavioral consistency of serial offenders has been successfully conducted for burglary (e.g., Bennell & Canter, 2002;Bennell & Jones, 2005;Goodwill & Alison, 2006;Green, Booth, & Biderman, 1976;Yokota & Canter, 2004), arson (e.g., Santtila, Fritzon, & Tamelander, 2005), sexual assault (e.g., Canter et al., 1991;Deslauriers-Varin & Beauregard, 2013;Grubin, Kelly, & Ayis, 1997;Grubin, Kelly, & Brunsdon, 2001;Knight, Warren, Reboussin, & Soley, 1998), robbery (e.g., Woodhams & Toye, 2007), and homicide (e.g., Melnyk, Bennell, Gauthier, & Gauthier, 2011;Salfati & Bateman, 2005). Within these offense types, the most consistent offending behaviors have been the distance an offender traveled to the crime, the time interval between offenses, and a combination of related behaviors committed at the crime scene, known as the modus operandi or offense style 1 (e.g., Markson, Woodhams, & Bond, 2010;Tonkin, Woodhams, Bull, Bond, & Palmer, 2011). ...
Article
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This study evaluates the behavioral consistency in offending styles among a sample of serial burglars from the United States. Three popular specialization analyses—Jaccard’s coefficient, the forward specialization coefficient (FSC), and the Diversity (D) index—are used to compare if, and how much, variation exists in the behavior of serial burglars committing different styles of offenses, among the three analyses. Results show that there is variation across the analyses, with the FSC and D index suggesting serial burglars are relatively consistent in their burglary offense styles. However, burglars with organized and disorganized offense styles are more consistent in behavior across offenses than burglars who committed opportunistic and interpersonal style offenses. These findings have important methodological implications for criminological research, and practical implications for policing and crime linkage analysis.
... Bernasco, 2008;Goodwill & Alison, 2006;Markson et al., 2010;Tonkin et al., 2008;. In recent studies (Deslauriers-Varin & Beauregard, 2013Lundrigan et al., 2010), the consistency displayed by serial sex offenders with regard to the crime location and characteristics of the crime site selected (i.e. environmental consistency) was also examined. ...
... Faced with more criminal opportunities, these offenders can gain experience and knowledge, which allows them to become more specialised, with time, in particular crime types more suited to their preferences and skills (e.g. Blumstein et al., 1988;Deslauriers-Varin & Beauregard, 2013;Woodhams & Labuschagne, 2012b). From this, consistency should then be found for more prolific offenders with long crime series. ...
... Please note that the current study is based on a dataset used in prior published studies examining serial sex offenders' consistency(Deslauriers-Varin & Beauregard, 2013;Harbers et al., 2012). ...
... Associated with the emergence of crime linkage, researchers started to question whether offenders are in fact consistent in the way they commit their crimes across their series (behavioral consistency) and if behavioral evidences could be used to reliably link unsolved crimes. Yet, a review of the scientific literature reveals that the identification of offending behaviors and components to be used to link crimes remains elusive due to the scarcity of research on the behavioral consistency assumption (Deslauriers-Varin & Beauregard, 2013;Sorochinski & Salfati, 2010). Moreover, studies on behavioral consistency are based on various conceptual, methodological, and analytical procedures, which further limit the conclusion that can be drawn (see Deslauriers-Varin & Beauregard, 2013;Woodhams & Labuschagne, 2012). ...
... Yet, a review of the scientific literature reveals that the identification of offending behaviors and components to be used to link crimes remains elusive due to the scarcity of research on the behavioral consistency assumption (Deslauriers-Varin & Beauregard, 2013;Sorochinski & Salfati, 2010). Moreover, studies on behavioral consistency are based on various conceptual, methodological, and analytical procedures, which further limit the conclusion that can be drawn (see Deslauriers-Varin & Beauregard, 2013;Woodhams & Labuschagne, 2012). Nevertheless, findings from recent studies indicate that, when examining suitable behavioral domains or individual behaviors, high consistency exists among offenders' behaviors and that these behaviors can be thus used to successfully link serial crimes (Bennell & Jones, 2005). ...
... Hence, this result does not mean that one offender is consistently using the same site to commit the offense from one crime to the other. In fact, it was previously found that the victim release site characteristics showed lower level of individual consistency compare to the encounter site characteristics (see Deslauriers-Varin & Beauregard, 2013). Instead, it means that victim release sites selected by offenders for the first few crimes of their series are not different from those selected for any other subsequent crimes committed by the offenders. ...
... escalating in degree or switching from one behavioural subtype to another) rather than isolated behaviours. Three additional studies (Hewitt and Beauregard 2014;Leclerc et al. in press;Lussier et al. 2008) used transition matrices to estimate the probability of behaviours used in the first crime to be repeated 1 Bateman and Salfati 2007;Bennell and Canter 2002;Bennell and Jones 2005;Bennell et al. 2009;Bouhana et al. 2014;Burrell et al. 2012Burrell et al. , 2015Canter et al. 1991;Deslauriers-Varin and Beauregard 2013;Ellingwood et al. 2013;Fox and Farrington 2014;Green et al. 1976;Grubin et al. 2001;Harbers et al. 2012;Hewitt and Beauregard 2014;Kearns et al. 2011;Leclerc et al. in press;Lussier et al. (2008); Markson et al. 2010;Melnyk et al. 2011;Salfati and Bateman 2005;Salfati et al. 2014;Salo et al. 2012;Santtila et al. 2004Santtila et al. , 2005bSanttila et al. 2008Slater et al. 2015;Sorochinski and Salfati 2010;Tonkin & Woodhams 2015;Tonkin et al. 2008Tonkin et al. , 2011Tonkin et al. , 2012aTonkin et al. , 2012bWinter et al. 2013;Woodhams and Labuschagne 2011;Woodhams and Toye 2007;Woodhams et al. 2007aWoodhams et al. , 2008 in subsequent crimes of persistent sexual offenders. The findings suggested that changes in offenders' behaviours occur in a fairly predictable manner as a function of the offender's level of self-control as well as situational constraints. ...
... It is also important to note that, whilst some previous studies report higher levels of consistency in violence and control behaviours (e.g. Bennell et al. 2009;Deslauriers-Varin and Beauregard 2013;Harbers et al. 2012), as highlighted in the 'Introduction', these studies only examined consistency in linked pairs of crime. As shown here, when only two crimes from a series are examined, the levels of consistency may be as high as 90% during some transitions, however, when consistency is examined across four crimes in the series, these levels are reduced substantially, underscoring that offenders should not be regarded as either consistent or inconsistent based on a pair of crimes from their series. ...
Article
Whilst investigative use of behavioural evidence to help link and solve serial offences has long been in use, the empirical and theoretical grounds for whether and how to use this evidence effectively have begun to emerge only in recent decades. The present study empirically tested (a) the potential for effectively differentiating between rape offence crime scenes using quantitative and qualitative distinctions within the behavioural dimensions of control, violence, and sexual activity, and (b) the extent to which redefining behavioural consistency more broadly to include dynamic trajectories of behavioural change may be more effective than limiting this definition to behavioural stability. Results confirmed that sexual offences can be successfully differentiated based on the specific degree and subtype of these behavioural dimensions present in each crime scene. The analysis of consistency and behavioural trajectories showed that whilst none of the offenders exhibited complete consistency across behavioural dimensions, a subsample of offenders remained fully consistent in at least one. Furthermore, of those who were not consistent, the vast majority followed an identifiable trajectory of change. Findings are discussed in the context of psychological theories of behavioural consistency as well as practical aspects of advancing the utility of behavioural linkage.
... The first is that the criminals act consistently. While there might be slight variations in a criminal's behavior as the current goals, situational characteristics, and past learning influence each outcome (Woodhams et al., 2007b), a large body of literature suggests that there is sufficient consistency in some behavioral variables (especially site selection) to allow successful linkage analysis (Bennell and Canter, 2002;Bennell and Jones, 2005;Bernasco, 2008;Bouhana et al., 2014;Deslauriers-Varin and Beauregard, 2013;Goodwill and Alison, 2006;Grubin et al., 2001;Harbers et al., 2012;Johnson et al., 2009;Tonkin et al., 2008;Woodhams and Toye, 2007). ...
... A common approach to alleviate the potential bias is to form linked pairs from only a small number (e.g., 2) of crimes from each series (Bennell and Canter, 2002;Markson et al., 2010). While this approach does treat each series equivalently, it reduces the amount of data used to build our models (Deslauriers-Varin and Beauregard, 2013). Instead, we use all N linked pairs from a crime series, but weight each pair by 1/N . ...
Article
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The object of this paper is to develop a statistical approach to criminal linkage analysis that discovers and groups crime events that share a common offender and prioritizes suspects for further investigation. Bayes factors are used to describe the strength of evidence that two crimes are linked. Using concepts from agglomerative hierarchical clustering, the Bayes factors for crime pairs are combined to provide similarity measures for comparing two crime series. This facilitates crime series clustering, crime series identification, and suspect prioritization. The ability of our models to make correct linkages and predictions is demonstrated under a variety of real-world scenarios with a large number of solved and unsolved breaking and entering crimes. For example, a naive Bayes model for pairwise case linkage can identify 82% of actual linkages with a 5% false positive rate. For crime series identification, 74%-89% of the additional crimes in a crime series can be identified from a ranked list of 50 incidents.
... Not only are these types of crimes the most difficult to solve by the police because there is no direct link leading investigators to the suspect, but they also cause considerable panic and fear within the community as anyone could fall victim to the offender. As the police are often faced with many obstacles when solving stranger sexual assaults (e.g. a lack of investigative clues and pressure from the community to apprehend the suspect; Harbers, Deslauriers-Varin, Beauregard, & Van Der Kemp, 2012), it is sometimes necessary to refer to offender profiling in the absence of a confession, eyewitness, or physical evidence (Deslauriers-Varin & Beauregard, 2013), specifically crime linkage analysis, to aid in these efforts. Once analysts have linked crimes with a high 'degree of match' (Grubin, Kelly, & Brunsdon, 2001, p. 2), through either physical evidence, offender description, or crime scene behaviour (Rossmo, 2000), and have determined the likelihood of the similarity between cases to be more than what would occur by chance, law enforcement officials then become preoccupied with whether or not the serial offender will escalate in the severity of his actions with subsequent victims. ...
... One of the main objectives of the present study is to determine whether or not there is evidence of escalation (i.e. an increase in the severity of the crime rather than an increase in the frequency of offending) or de-escalation from one victim to the next within this group of serial stranger offenders, especially as it pertains to the types of sexually intrusive acts committed and level of physical force used by the offender throughout the crime commission process. sexual assaults (Deslauriers-Varin & Beauregard, 2013). One of these means, which is part of the shift towards more intelligence-led policing, is known as case linkage. ...
Article
A series of stranger sexual assaults poses considerable obstacles for law enforcement officials. One such preoccupation is concerned with whether or not the offender will escalate in the severity of his behaviours with subsequent victims. The current study uses transition matrices to address whether or not the offending patterns of 72 serial stranger sex offenders change from one victim to the next as it pertains to their sexual acts and level of physical force used during the crime. Findings indicate that stability, specifically the offender's intrusive sexual acts and use of physical force, and versatility are present in this sample's offending patterns. To explain changes in offending patterns between victims, multinomial regression analyses indicate that situational factors and modus operandi strategies are important considerations. Implications for investigations are discussed. Copyright © 2013 John Wiley & Sons, Ltd.
... La consistencia conductual en delincuentes seriales ha sido estudiada en el caso de homicidios (Salfati & Bateman, 2005;Bateman & Salfati, 2007;Sorochinski & Salfati, 2010;Salfati, Horning, Sorochinski & Labuschagne, 2015), intrusión en propiedades con fines de robo (Bouhana, Johnson & Porter, 2016;Fox & Farrington, 2016), y agresores sexuales (Lundrigan, Czarnomski, & Wilson, 2010;Harbers, Deslauriers-Varin, Beauregard & Kemp, 2012;Deslauriers-Varin & Beauregard, 2013, 2014a, 2014bHewitt & Beauregard, 2014;Oziel, Goodwill & Beauregard, 2015). En general, estos estudios concluyen, de una forma metodológicamente aceptable, que los delincuentes seriales tienden a repetir sus conductas crimen tras crimen (Janosch & Soto, 2018; Janosch, Pérez-Fernández & Soto-Castro, 2018a y 2018b; Janosch, Pérez-Fernández & Soto-Castro, 2020; Pérez-Ramírez, Giménez-Salinas, González-Álvarez, Soto-Castro, 2021). ...
Article
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Propósito: Estudiar la consistencia en las conductas de los agresores sexuales desconocidos y seriales en la escena del crimen, y la influencia de los factores situacionales. Método: Se analizan las conductas en la escena del crimen de 18 agresores sexuales desconocidos y seriales, que cometieron al menos 54 agresiones sexuales. Se han correlacionado con factores situacionales. Se ha estudiado también la consistencia de cada una de esas conductas. Resultados: Algunas conductas de los delincuentes están influidas por factores situacionales y, a la inversa, algunos factores situacionales pueden estar influidos por tales conductas. Algunas conductas que, prima facie, no están influenciadas por los factores situacionales son consistentes. Una excepción son las conductas sexuales del delincuente. Conclusión: Este análisis confirma, aunque limitadamente, relaciones conductuales esperables, pero nunca antes estudiadas, en una muestra española de agresores sexuales seriales y desconocidos.
... La consistencia conductual en delincuentes seriales ha sido estudiada en el caso de homicidios (Salfati & Bateman, 2005;Bateman & Salfati, 2007;Sorochinski & Salfati, 2010;Salfati, Horning, Sorochinski & Labuschagne, 2015), intrusión en propiedades con fines de robo (Bouhana, Johnson & Porter, 2016;Fox & Farrington, 2016), y agresores sexuales (Lundrigan, Czarnomski, & Wilson, 2010;Harbers, Deslauriers-Varin, Beauregard & Kemp, 2012;Deslauriers-Varin & Beauregard, 2013, 2014a, 2014bHewitt & Beauregard, 2014;Oziel, Goodwill & Beauregard, 2015). En general, estos estudios concluyen, de una forma metodológicamente aceptable, que los delincuentes seriales tienden a repetir sus conductas crimen tras crimen (Janosch & Soto, 2018; Janosch, Pérez-Fernández & Soto-Castro, 2018a y 2018b; Janosch, Pérez-Fernández & Soto-Castro, 2020; Pérez-Ramírez, Giménez-Salinas, González-Álvarez, Soto-Castro, 2021). ...
Article
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Filiación Institucional (1) Resumen Propósito: Estudiar la consistencia en las conductas de los agresores sexuales desconocidos y seriales en la escena del crimen, y la influencia de los factores situacionales. Método: Se analizan las conductas en la escena del crimen de 18 agresores sexuales desconocidos y seriales, que cometieron al menos 54 agresiones sexuales. Se han correlacionado con factores situacionales. Se ha estudiado también la consistencia de cada una de esas conductas. Resultados: Algunas conductas de los delincuentes están influidas por factores situacionales y, a la inversa, algunos factores situacionales pueden estar influidos por tales conductas. Algunas conductas que, prima facie, no están influenciadas por los factores situacionales son consistentes. Una excepción son las conductas sexuales del delincuente. Conclusión: Este análisis confirma, aunque limitadamente, relaciones conductuales esperables, pero nunca estudiadas, en una muestra española de agresores sexuales seriales y desconocidos. Palabras Clave Agresión sexual, desconocido, decisiones conductuales, situación, consistencia conductual. Abstract Purpose: To study the consistency in crime scene behaviors of unknown and serial sexual offenders and the influence of situational factors. Methods: The crime scene behaviors of 18 unknown and serial sexual offenders, who committed at least 54 sexual assaults, were analyzed. They have been correlated with situational factors. The consistency of each of these behaviors was also studied. Results: Some offenders' behaviors are influenced by situational factors and, conversely, some situational factors may be influenced by such behaviors. Some behaviors that, prima facie, are not influenced by situational factors are consistent. An exception is offender sexual behaviors. Conclusion: This analysis confirms, albeit to a limited extent, expected but never studied behavioral relationships in a Spanish sample of serial and unknown sex offenders.
... In most contexts, serial criminality is defined as committing two Slater et al., 2014) or sometimes three or more separate incidents at two points in time for a certain population of interest (Edelstein, 2016). Serial criminality most often implies adjudication in the criminal justice system (Deslauriers-Varin & Beauregard, 2013;Rebocho & gonÇalves, 2012), meaning that the offender is connected to two or more crimes via arrest and/or conviction. ...
... The sex offenses included a wide range of behaviors, from indecent exposure to rape, and included offenses against children and adults. They could have occurred at the offender's home, the victim's home, or elsewhere [93][94][95][96][97]. Sex offenders' strategies for identifying, approaching, and attacking victims vary widely from extended grooming to opportunistic "blitz" attacks [98][99][100][101][102]. Offenders might identify their victims through social networks (online or offline) or search for victims in target rich environments such as near schools or night-time economy districts [94,96,97,[102][103][104]. All these factors would lead to variation in the relationship between offenders' activity spaces and their crime locations. ...
Article
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It is well established that offenders' routine activity locations (nodes) shape their crime locations, but research examining the geography of offenders' routine activity spaces has to date largely been limited to a few core nodes such as homes and prior offense locations, and to small study areas. This paper explores the utility of police data to provide novel insights into the spatial extent of, and overlap between, individual offenders' activity spaces. It includes a wider set of activity nodes (including relatives' homes, schools, and non-crime incidents) and broadens the geographical scale to a national level, by comparison to previous studies. Using a police dataset including n=60,229 burglary, robbery, and extra-familial sex offenders in New Zealand, a wide range of activity nodes were present for most burglary and robbery offenders, but fewer for sex offenders, reflecting sparser histories of police contact. In a novel test of the criminal profiling assumptions of homology and differentiation in a spatial context, we find that those who offend in nearby locations tend to share more activity space than those who offend further apart. However, in finding many offenders' activity spaces span wide geographic distances, we highlight challenges for crime location choice research and geographic profiling practice.
... Ainsi, les résultats de la présente étude pourraient être le fait d'un faible nombre d'agresseurs d'enfants qui emmènent leurs victimes dans les mêmes lieux extérieurs pour commettre leurs agressions puisque ces lieux sont relativement peu exposés et peu à risque. Des études précédentes portant sur la constance des comportements de délinquants sexuels et de leurs lieux choisis soutiennent en effet cette proposition (voir par exemple Deslauriers-Varin et Beauregard, 2013, 2014a, 2014bLundrigan, Czarnomski et Wilson, 2010 ;Santtila, Junkkila et Sandnabba, 2005). Les conclusions de ces travaux indiquent que les auteurs de crimes sexuels en série préfèrent choisir les mêmes lieux géographiques (centres commerciaux, quartiers, etc.) ou des lieux ayant des caractéristiques similaires. ...
Article
Les études portant sur les crimes et les lieux ont toujours insisté sur l’importance de comprendre le profil spatial des crimes à l’aide d’unités d’analyse de plus en plus réduites. Même si de nombreuses études ont adopté cette perspective, peu se sont intéressées spécifiquement aux crimes à caractère sexuel. La présente étude se sert des données d’incidents enregistrés par la police pour étudier la distribution spatiale des infractions sexuelles ayant eu lieu entre le 1 er janvier 2016 et le 31 décembre 2018 à Austin, au Texas (N = 1381). Les infractions ont d’abord été divisées selon l’âge des victimes (enfant ou adulte) et le type d’acte sexuel perpétré (infraction sexuelle avec pénétration, avec contact et sans contact), ensuite trois mesures de concentration spatiale, des analyses de noyaux de densité et des analyses de dispersion spatiale ont été réalisées. Les résultats montrent que les infractions sexuelles commises contre des enfants et des adultes étaient concentrées dans l’espace, mais que leur degré de concentration dépendait du type d’acte commis. De plus, les analyses de dispersion spatiale semblent montrer que les segments de rue (et les intersections) où ont lieu de telles infractions diffèrent en fonction de la nature de l’acte sexuel perpétré. Les implications pour la prévention situationnelle et le maintien de l’ordre ( policing ) seront discutées.
... Simple maps that display the locations where crimes or concentrations of crimes have occurred can be used to help direct patrols to places they are most needed [16] . Geography provides help to identify geo-demographic role in crime expansion or contraction and give solutions to overcome crime escalation [17] . ...
Article
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Continuity and severity of homicide incidents in Karachi in actuality is a sign of negligence by administration, one of the components of Routine Activity Theory. Looking at other crimes, like car and motorbike thefts or cell phone snatchings, homicide incidents are much more shocking, having fluctuated from 550-495, 1705, 2258, 2062, 2002, 1820, 918 and 450, respectively between 2009 and 2017. Policy makers and police departments might use GIS to observe trends in criminal activity through geo-coded data and maps may prove significant in solving criminal cases. In this connection, the half square cells configuration has been introduced for evaluation of geographic core of the study area regarding homicides. The study has also sought to reduce the perception that the entire city is enveloped in homicides rather that specific parts of the city are scourged by this heinous crime.
... Ainsi, les résultats de la présente étude pourraient être le fait d'un faible nombre d'agresseurs d'enfants qui emmènent leurs victimes dans les mêmes lieux extérieurs pour commettre leurs agressions puisque ces lieux sont relativement peu exposés et peu à risque. Des études précédentes portant sur la constance des comportements de délinquants sexuels et de leurs lieux choisis soutiennent en effet cette proposition (voir par exemple Deslauriers-Varin et Beauregard, 2013, 2014a, 2014bLundrigan, Czarnomski et Wilson, 2010 ;Santtila, Junkkila et Sandnabba, 2005). Les conclusions de ces travaux indiquent que les auteurs de crimes sexuels en série préfèrent choisir les mêmes lieux géographiques (centres commerciaux, quartiers, etc.) ou des lieux ayant des caractéristiques similaires. ...
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Les études portant sur les crimes et les lieux ont toujours insisté sur l’importance de comprendre le profil spatial des crimes à l’aide d’unités d’analyse de plus en plus réduites. Même si de nombreuses études ont adopté cette perspective, peu se sont intéressées spécifiquement aux crimes à caractère sexuel. La présente étude se sert des données d’incidents enregistrés par la police pour étudier la distribution spatiale des infractions sexuelles ayant eu lieu entre le 1er janvier 2016 et le 31 décembre 2018 à Austin, au Texas (N = 1381). Les infractions ont d’abord été divisées selon l’âge des victimes (enfant ou adulte) et le type d’acte sexuel perpétré (infraction sexuelle avec pénétration, avec contact et sans contact), ensuite trois mesures de concentration spatiale, des analyses de noyaux de densité et des analyses de dispersion spatiale ont été réalisées. Les résultats montrent que les infractions sexuelles commises contre des enfants et des adultes étaient concentrées dans l’espace, mais que leur degré de concentration dépendait du type d’acte commis. De plus, les analyses de dispersion spatiale semblent montrer que les segments de rue (et les intersections) où ont lieu de telles infractions diffèrent en fonction de la nature de l’acte sexuel perpétré. Les implications pour la prévention situationnelle et le maintien de l’ordre (policing) seront discutées. The crime and place literature has consistently emphasized the importance of understanding spatial patterns of crime using increasingly smaller spatial units of analysis. Despite the growing number of studies that have used this perspective, very few of them have investigated sexual offences specifically. The current study uses police event data to investigate the spatial distribution of sexual offences that occurred between January 1, 2016 to December 31, 2018 in the city of Austin, Texas (N=1381). Disaggregating offences first by victim age (child versus adult) and then type of sexual act perpetrated (penetration, sexual contact, and sexual non-contact offences), three measures of spatial clustering, kernel density analyses, and a spatial point pattern test were used. Findings indicate that sexual offences perpetrated against children and adults were spatially concentrated, but the degree to which they clustered depended upon the type of sexual act committed. Furthermore, spatial point pattern findings suggested that the street segments (and intersections) affected by sexual crime differed according to the nature of the sexual act committed. Implications for situational crime prevention and policing are discussed.
... C'est dans ce contexte que, durant le dernier quart du xx e siècle, s'est développée une nouvelle forme d'analyse criminelle basée sur l'utilisation d'outils informatiques et d'approches explicatives novatrices (Collins, Johnson, Choy, Davidson et MacKay, 1998 ;Martineau et Corey, 2008 ;Ribaux, 2014). L'un des domaines dans lesquels ce phénomène peut être le mieux observé est celui de l'analyse de la délinquance sexuelle sérielle, qui peut être opérationnalisé par la présence de plusieurs événements criminels, généralement au moins deux (voir par exemple Beauregard, 2005 ;Beauregard, Proulx, Rossmo, Leclerc et Allaire, 2007 ;Chopin et Aebi, 2018 ;Deslauriers-Varin et Beauregard, 2013), séparés par un intervalle de temps et commis par le même auteur (Fox et Levin, 1994 ;Geberth, 1986). Dans ce domaine, des outils toujours plus puissants et enregistrant un nombre d'informations toujours plus important ont été mis sur pied afin d'aider les policiers dans les enquêtes les plus complexes. ...
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This study focuses on obtaining a better understanding of the amount of data required by a crime linkage system to identify serial violent crimes. The key objective of the research was to empirically test and discuss the relevance of reducing the content necessary to use these tools. Data for the current study was extracted from a French violent crime linkage database (ViCLAS). Analysis focused on the most used variables in the context of a sexual assault. Descriptive and factorial analysis were used to identify what kind of information is collected by the police and how it could be reduced by aggregating correlated data. Findings show that approximately 65 % of the types of information collected are used in less than 5 % of sexual assault cases. Results of factorial analysis show that it is possible to drastically reduce the information needed to use the tool effectively. Practical implications of these findings for sexual assault investigations are discussed.
... To improve criminal investigation of stranger offenders which is typically short of witnesses and physical evidence (Deslauriers-Varin & Beauregard, 2013;ter Beek et al., 2010) it is important, firstly, to be fully familiar with stranger sexual offences. A comprehensive understanding will enable us to establish classification typologies or decision systems that will guide us through the decision-making process of the police investigation. ...
Article
We have analysed the information in 342 police reports of stranger sexual offences recorded in 2010. We have carried out a multiple correspondence analysis and a cluster analysis using modus operandi variables to identify differential profiles in these types of sexual offences. We have come up with three profiles of stranger sexual offences, which concur in the two techniques used. By analysing the personal variables of the offenders with such profiles, we have found differences in terms of the offender’s country of origin and age. We will discuss the consequences of these results on the police investigation of stranger sexual offences.
... Néanmoins, certains auteurs se contentent d'un minimum de deux homicides (Brooks, Devine, Green, Hart, & Moore, 1988;Canter & Larkin, 1993), tandis que d'autres vont exiger jusqu'à quatre (Hickey, 1990). De même, dans le domaine des agressions sexuelles, les chercheurs ont tendance à qualifier comme agresseur sériel celui qui aura commis plus d'une agression durant une certaine période de temps (Beauregard, 2005;Beauregard, Proulx, Rossmo, Leclerc, & Allaire, 2007;Deslauriers-Varin & Beauregard, 2013;Harbers, Deslauriers-Varin, Beauregard, & Van Der Kemp, 2012). Par conséquent, ce minimum de deux agressions, séparées par un intervalle de temps, est utilisé dans notre étude pour définir la sérialité des agresseurs sexuels. ...
Article
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This study examines the concurrent validity of the Violent Crime Linkage Analysis System (ViCLAS) by comparing the percentage of serial sexual offenders identified by this instrument with the one revealed by research based on self-reported studies conducted with incarcerated sexual offenders. Data are taken from the ViCLAS database used by the French Police which includes 3,500 offenders and 3,901 cases of extra familial sexual crimes covering the years 1979 to 2013. The results show that, according to ViCLAS, 13.5 % of the offenders who assaulted victims of less than 15 years were identified as serial offenders by ViCLAS, while the percentage is 5.75 % for victims of 15 years or more. Major differences exist between these results and those of self-reported survey indicating a validity problem for ViCLAS.
... First, being able to determine that offence behaviors are predictive of criminal history, but also specific behaviors that can assist in prioritizing potential nominals is a great asset to sexual offence investigations. This could improve the detection and apprehension rates of sexual offenders, but could also significantly reduce both time and financial costs, resulting in investigative resources being employed more efficiently (Deslauriers-Varin & Beauregard, 2013;Bennell, Jones & Melnyk, 2009). The current findings are of use to BIAs, who are reliant on statistical information to support any behavioral claims made (Rainbow & Gregory, 2011). ...
Article
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Davies, Wittebrood, and Jackson (1997) were among the first to investigate whether offense behaviors are predictive of criminal history, with the findings of their paper then utilized by the National Crime Agency (NCA) Behavioral Investigative Advisors (BIAs) when assisting rape investigations. The aim of the study was to replicate this seminal paper with a larger contemporary sample of U.K. stranger rapists as identified by NCA. Data from 474 adult male stranger rapists were obtained in relation to 22 crime scene behaviors and nine preconviction variables. Results indicated significant differences between the Davies et al. original data set and this contemporary data set in both the behaviors and the preconvictions they displayed. The contemporary sample was significantly less likely to use sighting precautions, use violence, and take fingerprint precautions. This sample was also significantly less likely to have any of the preconviction crime types, with the exception of drugs offenses. When exploring the current data set of stranger rapists, statistical analyses indicated a number of key offense behaviors that were able to predict the criminal history of stranger rapists. However, contrary to previous research, no behaviors were found to be associated with sexual offense preconvictions. The results highlight that behaviors and characteristics of stranger sex offenders have changed since the 1990s. The implications for practice are discussed.
... Indeed, the selection of locations and times to commit sexual crimes is not random and "irrational," but rather controlled and based on the available information and internal cost-benefit calculation of the perpetrator. For example, while the environmental decision-making involved in crime site selection might be influenced by dynamic factors, prior research has shown that sex crime perpetrators often use the same geographic and ecological space and tend to pattern themselves geographically and temporally (e.g., Beauregard, Proulx, Rossmo, Leclerc, & Allaire, 2007;Canter, 2000;Deslauriers-Varin, & Beauregard, 2013;2014b;Lundrigan, Czarnomski, & Wilson, 2010). In other words, whatever might be influencing the timing of the offense and the offense location is also influencing the timing and location of the perpetrator's subsequent offenses. ...
Chapter
Sexual assault and abuse are among the most heinous crimes that can be committed. However, these crimes are largely underreported worldwide. Despite this, research on the investigation of sexual assault and abuse cases has been slow to emerge and there exists an important gap between the current knowledge on sexual victimization and the police response to it. Research is required on many topics related to the investigation of sexual assault and abuse, including research that can improve the effectiveness of investigative interviews and the accurate identification and prioritization of suspects. The goal of the current chapter is to review current research efforts in these two areas –investigative interviewing and suspect identification and prioritization procedures – and to discuss some of the challenges associated with these tasks , and the investigation of sexual assault and abuse more generally (e.g., false allegations, false confessions, cognitive biases).
... 供建议 [3] 。这些研究使得环境犯罪学理论从宏观向微观逐渐发展,并从环境、城市规划等 角度研究犯罪发生的潜在诱因。 在环境犯罪学领域,人们已经提出了多种犯罪学理论。从社会解组理论到日常行为 理论、理性选择理论,再到破窗理论、犯罪场理论等多种犯罪学理论分别从不同的角度 对犯罪与时空环境之间的相互作用关系进行了阐述 (图 1) 。纵观各个环境犯罪学理论可 以看出,社会解组理论更加注重失控的时空环境对于区域范围内犯罪态势的影响。其分 析尺度为城市、地区。日常行为理论、理性选择理论等注重分析人的行为与周围空间环 境的关联关系。其分析尺度是以人的生活范围大小进行分析的。破窗理论、犯罪场等理 论则是针对某个固定的时空范围 (或时空对象) 及其拥有的时空特征对行为人做出选择 的影响进行分析的。其分析尺度为具体的空间对象 (如路灯、房屋、街角等) 。 不同的犯罪学理论适用的空间尺度不尽相同,其分析过程中选择的环境因子也会随 之发生变化。环境犯罪学理论的适用尺度正在由大向小逐渐发展。因此,在分析影响犯 罪的环境特征时,需要选择合适的犯罪学理论以指导因子的分析和尺度的选择。 2 犯罪空间特征与尺度 犯罪与环境是息息相关的 [4] 。早期犯罪学的研究主要从宏观的角度分析城市规划对于 预防犯罪的作用。王发曾等 [5] 从城市空间格局的角度,系统地研究了城市中治安盲区对于 犯罪的影响,在盲区分析与综合治理方面提出了一些重要的研究成果。此后,研究分别 从街道 [6][7][8] 、社区 [9] 、邻里 [10] 以及固定大小的格网 [11] 来分析犯罪与城市地理特征的关系。这 些研究从城市环境的角度出发,分析了城市或街道的地理特征与犯罪率的关联关系,为 宏观把握犯罪的分布特征提供了基础。 近年来,研究人员开始从微观的角度分析犯罪与不同地理因子的关联特征。比如拐 点 [12] 、医院 [13] 、路灯 [14] 、地铁站 [15] 、商店 [16] 、监控网络 [17][18] 等城市中的微观地物均可能对 犯罪的发生产生影响。这些研究从微观的角度出发,分析具体地物类型或目标对于犯罪 的影响。研究结论不仅解释了犯罪发生的机理,而且对于警力部署、犯罪心理分析等具 有重要的参考价值。 由以上研究可以看出,人们对于犯罪的影响因素从宏观的城市规划到中观的街道单 元,再到微观的房屋特征等多个空间尺度均开展了大量的研究工作。然而,由于没有考 虑尺度的影响,不同的研究会得到不同的分析结论。比如,Kautt 等 [19] 在大尺度上研究发 现靠近市中心、人口密度等因素与入室盗窃正相关,是入室盗窃的主要影响因素之一。 然而在微观尺度上,王子熙等 [20] 研究发现人口密度与入室盗窃率显著负相关;颜峻等 [21] 对入室盗窃空间分布与地理因素的关联性分析,发现在社区尺度上入室盗窃犯罪率与距 图 1 现有环境犯罪学理论比较 派出所距离没有显著相关性。而在房屋大小尺度的上,Groff 等 [22] 的实验结果表明:入室 盗窃与距警局的距离呈正相关性;Wang [23] 在研究犯罪率与工作便利性的关系时发现,就 业便捷度与犯罪率在人口普查区尺度上有很强的负相关。而在社区尺度上对相同的数据 进行回归分析时并未发现二者存在显著的相关性 [24][25] ...
Article
Current theoretical and empirical literature provides abundant knowledge about why and where crime takes place. However, few empirical studies analyze the scale applicability of the existing research. In order to get a better understanding of the relationship between burglary and sociodemographic and economic characteristics, this paper applies multiscale analysis to assess the stability of model parameters on different spatial scales. First, this paper summarizes the existing theories of environmental criminology, and concludes that each kind of theory can only be employed in a certain spatial scale. Thus, a more comprehensive explanation of crime needs more than one crime theory. Geographical factors associated with burglary also distinct between the results from different spatial scales. Therefore, multiscale analysis method may offer a more comprehensive and accurate analysis than single scale analysis in crime modelling. Second, using a recent burglary dataset from N city in southeast China, the current research applies a seemingly unrelated regression model to assess the stability of correlation coefficients between burglary and geographical factors among five spatial scales (residential area, neighborhood, community, street and district). After Wald's test for a significant test of correlation coefficients, the experimental result shows that, some correlation coefficients do not vary, while others vary significantly. Environmental criminology theories at different spatial scales explain the changes of these correlation coefficients. Finally, compared with the inversion results from single spatial scales, those integrating five spatial scales show a higher accuracy. The result demonstrates that, in the research of environmental criminology, the theories, geographical factors and spatial distribution inversion all depend on scale change. Multiscale analysis method performs better in geographical analysis, theory research and crime inversion than single scale analysis.
... First, the predisposition to offend is reduced as the author moves away from his or her base or place of residence [7][8][9]. Besides, the distance an aggressor can go through to commit a crime is often similar to the distance covered in consecutive ones [13]. Therefore, crimes committed by the same aggressor will have a tendency to focus on the surroundings of his or her base and around a comfort zone [6]. ...
Article
Geographical profiling has been developed within the scientific community as a useful criminal investigation method. Its application in violent crimes has demanded a theoretical review and a valuation about the methodology used until now. This article offers a review of the basic concepts of geographical profiling and its evolution over time. To do that, there is an analysis of the main sustaining theories, such as environmental criminology or the circle theory and the main tools developed as computer software. Finally, it also covers a critical review about geographical profiling and its possible developments in the future.
... From the descriptions of the aforementioned subtypes, it becomes clear that the environment plays a very important role in where crimes are likely to take place. Despite Rossmo's (2000) typology serving as an integral part of many subsequent research studies (e.g., Deslauriers-Varin & Beauregard, 2013;Rebocho & Gonçalves, 2012), few empirical studies have investigated the validity of these search strategies, especially with particular types of offenders. 1 As such, the goal of this study is to use latent class analysis (LCA) to test for the external validity of Rossmo's (2000) hunter, poacher, troller, and trapper types with a sample of serial stranger sexual offenders. ...
Article
Past research on the spatial mobility of serial offenders has generally found that these individuals make calculated decisions about the ways in which they come into contact with suitable victims. Within the geographic profiling literature, four victim-search methods have been theorized that describe how serial predatory offenders hunt for their victims: hunter, poacher, troller, and trapper. Using latent class analysis, the aim of this study is to test whether this theoretical typology can be empirically derived using data that were collected from both police files and semi-structured interviews with 72 serial sex offenders who committed 361 stranger sexual assaults. Empirical support is found for each of the aforementioned victim-search methods, in addition to two others: indiscriminate opportunist and walking prowler. Chi-square analyses are also conducted to test for associations between this typology and characteristics of the offense such as victim information, environmental factors, and the offender’s modus operandi strategies. Findings from these analyses suggest that the types of victims and environments targeted by the offender, as well as the behaviors that take place both before and during the offense, are dependent upon the offender’s victim-search strategy. Although the theoretical hunter, poacher, troller, and trapper were intended to describe the victim-search methods of serial violent predators more generally, the finding that these strategies exist along with two others in this sample of sexual offenders may indicate that search behavior is specific to certain crime types. Furthermore, these findings may be of assistance in the investigation of stranger sexual assaults by providing law-enforcement officials with possible clues as to the characteristics of the unknown suspect, the times and places likely targeted in any past or future events, and possibly even his base of operations.
... The study is not without some inherent methodological limitations. Recent research suggests that offenders displaying high levels of consistency are more likely to be detected or convicted (Deslauriers-Varin & Beauregard, 2013). Thus, there is a possibility that the levels of consistency present in the current study may be an over-representation of the levels displayed in undetected or unsolved sexual offences. ...
Article
The present study investigated behavioural consistency across sexual offending. Variations in behavioural consistency may arise from an increased influence of situational and contextual aspects. However, there is paucity of research exploring variations in behavioural consistency relative to the temporal sequence of the behaviour (e.g., occurring prior to or during the offence). A sample of 49 male serial stranger sexual offenders responsible for 147 offences across four temporal phases of a sexual offence was used in the current study. For each offence, four crime phases were identified: 1) pre-crime, 2) victim selection, 3) approach, and 4) assault. Behavioural consistency within and across offence series were examined utilizing Jaccard’s Coefficient and Receiver Operating Characteristics (ROC). Results indicated a high degree of behavioural consistency across all crime aspects; behaviours that were more dependent on situational influences were inherently less predictable and demonstrated to be less consistent. Further, increased behavioural consistency was associated with offender characteristics of a more stable nature. The implications of these findings are discussed.
... Although Lussier, Le Blanc, and Proulx (2005) discovered that rapists and child molesters showed divergence in their offending histories, with the latter exhibiting more specialised tendencies, Stander, Farrington, Hill, and Altham (1989) found that it was sexual offenders who were the most specialised. A high degree of offender consistency in serial stranger sex offenders was also found in the study by Deslauriers-Varin and Beauregard (2013). While Rojek and Erickson (1982) found evidence of specialisation for property offences and status offences, there was little indication of any specialisation within the other offence types in their sample. ...
Article
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Although previous research into specialisation has been dominated by the debate over the existence of specialisation versus versatility, it is suggested that research needs to move beyond the restrictions of this dispute. The current study explores the criminal careers of 200 offenders based on their criminal records, obtained from a police database in the North West of England, aiming to understand the patterns and nature of specialisation by determining the presence of differentiation within their general offending behaviours and examining whether the framework of Expressive and Instrumental offending styles can account for any specialised tendencies that emerge. Fifty-eight offences were subjected to Smallest Space Analysis. Results revealed that a model of criminal differentiation could be identified and that any specialisation is represented in terms of Expressive and Instrumental offending styles. © The Author(s) 2014.
Article
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Studies have shown that it is possible to link serial crimes in an accurate fashion based on the statistical analysis of crime scene information. Logistic regression (LR) is one of the most common statistical methods in use and yields relatively accurate linking decisions. However, some research suggests there may be added value in using classification tree (CT) analysis to discriminate between offences committed by the same vs. different offenders. This study explored how three variations of CT analysis can be applied to the crime linkage task. Drawing on a sample of serial sexual assaults from Quebec, Canada, we examine the predictive accuracy of standard, iterative, and multiple CTs, and we contrast the results with LR analysis. Our results revealed that all statistical approaches achieved relatively high (and similar) levels of predictive accuracy, but CTs produce idiographic linking strategies that may be more appealing to practitioners. Future research will need to examine if and how these CTs can be useful as decision aides in operational settings.
Chapter
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Offender profiling has been used by law enforcement agencies around the world for decades. Following homicide, offenses involving sexual assault are the second most common type of crime examined in offender profiling. Profiling sex crimes has successfully assisted investigators to find and convict sexual offenders and to deter future crimes. In this chapter, we focus on studies that developed profiles of sexual homicide and sexual assault to identify the personality characteristics, backgrounds, and mental states among offenders for these crimes, as well as analyze the similarities among sexual homicide and assault offenders, unique characteristics of these offenders, and how law enforcement can use these profiles to catch and prevent these offenders in the future.
Article
The crime and place literature has consistently emphasized the importance of understanding spatial patterns of crime using increasingly smaller spatial units of analysis. Despite the growing number of studies that have used this perspective, very few of them have investigated sexual offenses specifically. The current study uses police event data to investigate the spatial distribution of sexual offenses that occurred between January 1, 2016 and December 31, 2018 in Austin, Texas (N = 1381). Disaggregating offenses first by victim age (child versus adult) and then type of sexual act perpetrated (penetration, sexual contact, and sexual non-contact offenses), three measures of spatial clustering, kernel density analyses, and a spatial point pattern test are used. Findings indicate that sexual offenses perpetrated against children and adults are spatially concentrated, but the degree to which they cluster depends upon the type of sexual act committed. Furthermore, within each of these victim profiles, spatial point pattern findings suggest that the street segments (and intersections) affected by sexual crime differ according to the nature of the sexual act committed. Implications for situational crime prevention and policing are discussed.
Article
The finding that offenders tend to commit crime within relative proximity to their own residence has been well established in nearly 80 years of research. The usefulness of this area of research extends not only to the validation of environmental crime theories, but also offers to improve crime analysis capabilities, police investigative practice, and ultimately crime case clearances. Despite the considerable attention this area of study has received, much remains to be known about the factors which might influence variation in residence-to-crime (RTC) distances. One somewhat recently formalized idea is that offenders might be limited by the time that they have in which to commit crimes (such as by employment or family demands) and that this will constrict the geographic mobility of offenders as they operate within those time constraints. This study tested this time-constraint hypothesis on a sample of sex offense incidents (N = 157) from the state of New Jersey. Findings revealed limited support for the time-constraint thesis, before and after controlling for offender, situational and geographic characteristics. Implications for theory and practice are discussed.
Chapter
Although not well supported by empirical evidence, there exists a long tradition of beliefs suggesting that sex offenders suffer from mental disorders and are mainly driven by an uncontrollable impulse to sexually offend. Despite accumulating evidence showing the versatility of sex offenders, researchers have yet to examine their decision making similar to what has been done with other types of criminals (e.g., robbers, burglars, shoplifters, and car thieves). This chapter presents a review of the literature on the decision making involved in sexual crimes, specifically focusing on the decision making involved at the different crime stages-that is, before, during, and following the crime. Therefore, the goal is to take the reader through the different decision points an offender has to go through when committing a sexual crime. By doing so, this chapter aims to show that sex offenders are “reasoning” offenders similar to other types of criminals.
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In the 4 decades since offender profiling (OP) was established, hundreds of journal articles, books, book chapters, reports, and magazine articles have been published on the topic, and the technique has been used by countless law enforcement agencies around the globe. However, despite the popularity and extensive literature published on OP, very little is known about its evolution, current state, or findings of the field to date. Therefore, this study presents a systematic review and meta-analysis of 426 publications on OP from 1976 through 2016. Results of this systematic review suggest that there have been considerable improvements in the scientific rigor and self-assessment being conducted in the discipline, although in total, few studies have used a strong empirical approach to develop new profiles. Even fewer evaluations of the effectiveness of OP have been conducted. The first summary of offender profiles proposed for major crimes in OP literature is also presented, with results indicating some recurrent themes in profiles, but wide variations in the number, name, and description of the profiles often found. A meta-analysis of case linkage analysis research indicates that this area is statistically sophisticated, and has yielded moderate to strong accuracy rates for linking crimes to a single offender. Finally, the first analysis of the most prolific authors, researchers, departments, and outlets for OP research, and the methods, approach, and most cited publications in OP are identified. Suggestions for future research on OP and the potential impact that this may have on policy and practice are also discussed. (PsycINFO Database Record (c) 2018 APA, all rights reserved).
Article
Cambridge Core - Social Psychology - The Cambridge Handbook of Violent Behavior and Aggression - edited by Alexander T. Vazsonyi
Chapter
Evidence suggests that the majority of crime is committed by a minority of prolific serial offenders who pose a substantial risk to society. Behavioural Crime Linkage (BCL) has been proposed as one method to more effectively bring serial offenders to justice. BCL is a form of behavioural analysis that seeks to identify similarities in offender crime scene behaviour across two or more crimes so that evidence collected across multiple investigations can be combined, and thus helps the police to work in a more efficient way (thereby saving time and money). This chapter will introduce the concept of BCL, describe the different scenarios in which it is used during live police investigations, and briefly discuss empirical research in the area. The chapter will also explore how BCL relates to the concept of primary, secondary, and tertiary prevention, how BCL fits within the wider criminal justice process, and how BCL can support the work of other criminal justice agencies.
Article
Until recently, developmental criminologists have remained relatively silent about the issue of juvenile sex offending. Consequently, concepts and knowledge from the field developmental criminology are relatively unknown to researchers and practitioners working in the area of juvenile sex offending. In fact, for the past two or three decades, concepts and knowledge derived from clinical studies conducted with samples of adult sex offenders have been imported to guide the explanation and prevention of juvenile sex offending. This trend has led many to believe that today’s juvenile sex offenders are tomorrow’s adult sex offenders. This chapter builds on the research framework proposed by Dr. Marc LeBlanc by reviewing the state of knowledge on the development of juvenile sex offending. Developmental concepts are defined and proposed to organize findings of past research but also to stimulate and guide future prospective longitudinal studies aiming to describe, explain, and predict the development of juvenile sex offending.
Article
The present study examines consistency of crime behaviour among 347 sexual assaults committed by 69 serial sex offenders. This individual behaviour approach—the so-called signature approach—reveals which features of crime behaviour are consistent across a series and which features are not. The consistency scores were calculated using the Jaccard's coefficient. The results of this study indicate that there are some crime features of a serial sexual assault that can be useful for the purpose of linkage. Another important finding is that consistency scores for different variables within the same category can differ substantially. Moreover, serial sex offenders are more likely to be consistent in their environmental crime features when they are also consistent in their behavioural features, and vice versa. Serial sex offenders are also more likely to be consistent in the behavioural features of their assaults as the crime series gets longer. The implications of the results are discussed in relation to both research and practise
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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.
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This study aimed to investigate the case linkage principles, behavioural consistency and distinctiveness, with a sample of serial car thieves. Target selection, acquisition, and disposal behaviours, as well as geographical and temporal behaviours, were examined. The effects of temporal proximity and offender expertise were also investigated as moderating factors of behavioural consistency. As in previous case linkage research, geographical and some target selection behaviours were able to predict whether crime pairs are linked or unlinked at a statistically significant level. Crucially, it was also found that temporal behaviours demonstrate a significant capability to predict linkage status, a variable which has never before been applied to the prediction of linkage in serial car theft. Furthermore, it was demonstrated that changing the operationalisation of the behavioural domains can affect the results obtained. No support was found for the moderation of behavioural consistency on the basis of temporal proximity or expertise. Overall, the results support previous case linkage studies, furthering their practical applicability within the criminal justice system. Copyright © 2012 John Wiley & Sons, Ltd.
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Little is known about the stability of modus operandi (MO) in sexual offending. The authors studied a cohort of all sexual offenders released from prison into the Swedish community during the years from 1993 to 1997 (N = 1,303) and analyzed sexual reoffenders’ MO in terms of victim choice, offense nature, and severity, comparing prior offenses with those registered during an average 6-year follow-up. Stability in MO, explored with Cohen’s Kappa and Odds Ratios (ORs) as measures of agreement across registered sexual offenses, was high, specifically with respect to victim choice. Results are discussed in relation to sexual deviance and opportunity structure. The authors argue that assessment and management of sexual recidivism risk might benefit from information on offense MO. Furthermore, the results could inform police investigative strategies, such as linking multiple offenses committed by an unidentified offender.
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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.
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Much of the knowledge base on offense specialization indicates that, although there is some (short-term) specialization, it exists amidst much versatility in offending. Yet this general conclusion is drawn on studies using very different conceptualizations of specialization and emerges with data primarily through the first two to three decades of life. Using data on a sample of Dutch offenders through age 72 years, this article introduces and applies a new method for studying individual offender specialization over the life course. The results indicate that although, in general, individual offending patterns over the life course are diverse, there is also evidence of an age—diversity curve. Linking offense frequency trajectories to the estimated diversity index, the authors also examine distinct specialization patterns across unique trajectory groups. Implications for theory and research are outlined.
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Burglary victimization is associated with a temporary elevated risk of future victimization for the same property and nearby properties. Previous research suggests that often the initial and subsequent burglaries involve the same offenders. This paper tests this assertion, using data on detected residential burglaries during the period 1996—2004 in The Hague and its environs, in the Netherlands. It demonstrates that pairs of detected burglaries occurring in close proximity in space and time are much more likely to involve the same offenders than pairs that are not so related. Topics for future research and implications for the detection of burglaries are addressed.
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The present study aimed to identify dimensions of variation in serial homicide and to use these dimensions to behaviourally link offences committed by the same offender with each other. The sample consisted of 116 Italian homicides committed by 23 individual offenders. Each offender had committed at least two homicides. As some offenders had worked together and some murders involved more than one victim, there were 155 unique pairings of offenders and victims. Dichotomous variables reflecting crime features and victim characteristics were coded for each case. Using Mokken scaling, a nonparametric alternative to factor analysis, seven dimensions of variation were identified. Five of the dimensions described variations in the motivation for the killings. Three of these were concerned with aspects of instrumental motivation whereas two of the motivational scales described variations in sexual motivation. The two remaining dimensions dealt with the level of planning evident in the crime scene behaviour of the offender. Two dimensions were identified: one consisting of behaviours suggesting a higher level of control and another describing impulsiveness. Using discriminant function analysis with the dimensions as independent variables and the series an offence belonged to as dependent variable, 62.9% of the cases could be correctly assigned to the right series (chance expectation was 6.2%). The implications of the results for serial homicide investigations are discussed.
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To examine if serial homicide offenders are consistent across their crimes, a model was developed empirically that could be used to distinguish between crimes that were instrumental and those that were expressive. The first known three offences in each series of 69 US serial homicides committed by 23 offenders, were examined and the instrumental and expressive themes determined. Three models were then explored that test for consistency across these themes. The most liberal model was found to classify all of the offences effectively and to reveal complete consistency across the three crimes for all offenders. The implications of these results for offender profiling and further study of serial homicide are discussed. Copyright © 2005 John Wiley & Sons, Ltd.
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Personality psychologists have suggested that the context of a behaviour should be considered in studying behavioural consistency. They have operationalised this as studying ‘if (situation)–then (behaviour)’ contingencies and have demonstrated an association between situational similarity and behavioural consistency. Previous research of behavioural consistency in the forensic setting has tended to focus exclusively on the ‘then (behaviour)’ part of the contingency—the offender's behaviour. This paper considers methodological approaches that might be used to investigate whether situational similarity is associated with behavioural consistency, and to develop if–then contingencies. Seventy-eight offences by stranger sex offenders were subjected to constant comparison framework analysis to develop an offender behaviour checklist and a victim behaviour checklist, and a combination of constant comparison framework analysis and hierarchical cluster analysis were used to develop victim behavioural themes. Consistency in offender behaviour and similarity in victim behavioural themes (representing situational similarity) were measured using Jaccard's coefficient for offence pairs within 13 solved series of stranger sexual assaults. Correlational analyses were used to assess the relationship between situational similarity and behavioural consistency. Contrary to expectations, no relationship was found. The utility of linguistic computational programs in creating if(victim behaviour)–then(offender behaviour) contingencies was tested with encouraging results. However, little evidence of consistency in if(victim behaviour)–then(offender behaviour) contingencies was found within the offence series. Explanations are proposed for these novel findings and avenues for future research are suggested. Copyright © 2008 John Wiley & Sons, Ltd.
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Purpose . This paper is concerned with case linkage, a form of behavioural analysis used to identify crimes committed by the same offender, through their behavioural similarity. Whilst widely practised, relatively little has been published on the process of linking crimes. This review aims to draw together diverse published studies by outlining what the process involves, critically examining its underlying psychological assumptions and reviewing the empirical research conducted on its viability. Methods . Literature searches were completed on the electronic databases, PsychInfo and Criminal Justice Abstracts, to identify theoretical and empirical papers relating to the practice of linking crimes and to behavioural consistency. Results . The available research gives some support to the assumption of consistency in criminals' behaviour. It also suggests that in comparison with intra‐individual variation in behaviour, inter‐individual variation is sufficient for the offences of one offender to be distinguished from those of other offenders. Thus, the two fundamental assumptions underlying the practice of linking crimes, behavioural consistency and inter‐individual variation, are supported. However, not all behaviours show the same degree of consistency, with behaviours that are less situation‐dependent, and hence more offender‐initiated, showing greater consistency. Conclusions . The limited research regarding linking offenders' crimes appears promising at both a theoretical and an empirical level. There is a clear need, however, for replication studies and for research with various types of crime.
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The purpose of this study is to determine if readily available information about commercial and residential serial burglaries, in the form of the offender's modus operandi, provides a statistically significant basis for accurately linking crimes committed by the same offender. Logistic regression analysis is applied to examine the degree to which various linking features can be used to discriminate between linked and unlinked burglaries. Receiver operating characteristic (ROC) analysis is then performed to calibrate the validity of these features and to identify optimal decision thresholds for linking purposes. Contrary to crime scene behaviours traditionally examined to link serial burglaries, the distance between crime site locations demonstrated significantly greater effectiveness as a linking feature for both commercial and residential burglaries. Specifically, shorter distances between crimes signalled an increased likelihood that burglaries were linked. Thus, these results indicate that, if one examines suitable behavioural domains, high levels of stability and distinctiveness exist in the actions of serial burglars, and these actions can be used to accurately link crimes committed by the same offender. Copyright © 2005 John Wiley & Sons, Ltd.
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Whether criminals are specialized or versatile in their offending is a long-standing research area that has been recently revitalized by a paradigm that recognizes that both specialization and versatility characterize offending careers. Based on data from an enriched sample of 500 adult habitual criminals, the current study introduces a measure of relative specialization—the offense specialization coefficient—and a novel analytical technique called simultaneous quantile regression to further the study of specialization. Although offenders committed a mix of offenses, there was considerable and at times pronounced evidence of specialization. Age, sex, and arrest onset had differential predictive validity of specialization for eight crimes at the 75th and 95th quantiles. Implications and suggestions for future research are offered. KeywordsSpecialization–Versatility–Criminal careers–Career criminal–Typologies
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Case linkage involves identifying crime series on the basis of behavioral similarity and distinctiveness. Research regarding the behavioral consistency of serial rapists has accumulated; however, it has its limitations. One of these limitations is that convicted or solved crime series are exclusively sampled whereas, in practice, case linkage is applied to unsolved crimes. Further, concerns have been raised that previous studies might have reported inflated estimates of case linkage effectiveness due to sampling series that were first identified based on similar modus operandi (MO), thereby overestimating the degree of consistency and distinctiveness that would exist in naturalistic settings. We present the first study to overcome these limitations; we tested the assumptions of case linkage with a sample containing 1) offenses that remain unsolved, and 2) crime series that were first identified as possible series through DNA matches, rather than similar MO. Twenty-two series consisting of 119 rapes from South Africa were used to create a dataset of 7021 crime pairs. Comparisons of crime pairs that were linked using MO vs. DNA revealed significant, but small differences in behavioral similarity with MO-linked crimes being characterized by greater similarity. When combining these two types of crimes together, linked pairs (those committed by the same serial offender) were significantly more similar in MO behavior than unlinked pairs (those committed by two different offenders) and could be differentiated from them. These findings support the underlying assumptions of case linkage. Additional factors thought to impact on linkage accuracy were also investigated. KeywordsComparative case analysis–Linkage analysis–Behavioral linking–Sexual assault–Sexual offense
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Common error in bibliographies: "Étude comparative de la distribution florale dans une portion des Alpes et des Jura".
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This study investigates target selection scripts of 72 serial sex offenders who have committed a total of 361 sex crimes on stranger victims. Using latent class analysis, three target selection scripts were identified based on the victim's activities prior to the crime, each presenting two different tracks: (1) the Home script, which includes the (a) intrusion track and the (b) invited track, (2) the Outdoor script, which includes the (a) noncoercive track and the (b) coercive track, and (3) the Social script, which includes the (a) onsite track and the (b) off-site track. The scripts identified appeared to be used by both sexual aggressors of children and sexual aggressors of adults. In addition, a high proportion of crime switching was found among the identified scripts, with half of the 72 offenders switching scripts at least once. The theoretical relevance of these target selection scripts and their practical implications for situational crime prevention strategies are discussed.
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Ritual and signature are fantasy-driven, repetitive crime scene behaviors that have been found to occur in serial sexual homicide. Notwithstanding numerous anecdotal case reports, ritual and signature have rarely been studied empirically. In a national sample of 38 offenders and their 162 victims, we examined behavioral and thematic consistency, as well as the evolution and uniqueness of these crime scene actions. The notion that serial sexual murderers engage in the same rituals and leave unique signatures at every scene was not supported by our data. In fact, the results suggest that the crime scene conduct of this group of offenders is fairly complex and varied. Implications of these findings for forensic assessments and criminal investigations are discussed.
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The study of specialization in offending careers is relevant to the key theoretical issue of whether different types of offending reflect only one underlying theoretical construct (such as delinquent tendency) or several different constructs. This research improves on previous studies of specialization in offending careers in three ways: (1) It is based on the complete juvenile court careers of a very large sample of offenders (nearly 70,000). (2) It uses a fine-grained classification of 21 offense types. (3) It uses a new measure of the strength of specialization, the Forward Specialization Coefficient (FSC). Both transition matrices and offending careers are studied. The major findings from the transition matrices are (1) there was a small but significant degree of specialization in offending superimposed on a great deal of versatility; (2) the degree of specialization tended to increase with successive referrals, and this was not due to more versatile offenders dropping out; and (3) the relative extent to which offenders specialized in different offenses held for two jurisdictions (Maricopa County, Arizona and Utah), both sexes, and all ages. The analyses of offending careers showed that the most specialized offenses were runaway, burglary, motor vehicle theft, liquor violations, incorrigibility, curfew, truancy, and drugs. Nearly 20 percent of the offenders were identified as specialists. The conclusion is that, while offending was versatile to a first approximation, deliquency theories should attempt to explain specialization and specialists in order to yield more accurate quantitative predictions about offending careers.
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The present study examines consistency of crime behaviour among 347 sexual assaults committed by 69 serial sex offenders. This individual behaviour approach—the so-called signature approach—reveals which features of crime behaviour are consistent across a series and which features are not. The consistency scores were calculated using the Jaccard's coefficient. The results of this study indicate that there are some crime features of a serial sexual assault that can be useful for the purpose of linkage. Another important finding is that consistency scores for different variables within the same category can differ substantially. Moreover, serial sex offenders are more likely to be consistent in their environmental crime features when they are also consistent in their behavioural features, and vice versa. Serial sex offenders are also more likely to be consistent in the behavioural features of their assaults as the crime series gets longer. The implications of the results are discussed in relation to both research and practise
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A basic assumption underlying current public policy and crime-control efforts is that sex offenders are highly specialized and persistent. Using national data on about 10,000 sex offenders released from prison in 1994, this study explored this assumption by comparing the arrest patterns and cycles of sex offenders and other offenders. As a group and across various measures, sex offenders had low levels of specialization and persistence in offending in absolute and relative terms. Similar conclusions were reached when specific types of sex offenders (e.g., rapists, child molesters) were compared with other particular offenders (e.g., robbers, burglars, drug offenders), but the results were more measure dependent. Even among persistent serial sex offenders, rapists and child molesters were found to specialize only within a more predominant pattern of versatility across their criminal careers. These results are discussed in terms of their implications for future research and current public policy that are predicated on assumed specialization and persistence among sex offenders.
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This study presents a new approach to developing a typology of criminal activity. The distinguishing feature of the analysis is that it concentrates on determining types of activity rather than the amounts of activity over the life course. The methodology involves investigating criminal activity in a succession of five-year periods rather than the conventional approach of summarizing a ‘lifetime’ of crime. This provides scope for assessing changes and pathways of criminal activity as offenders grow older, and gives new insight into the concepts of specialization and versatility. The Home Office Offenders Index birth cohort for 1953 provided official conviction histories up to 1993 (age 40), and latent class analysis identified a fixed number of types of criminal behaviour separately for males and females. The patterns of offending varied markedly between males and females. Male offending (with nine identified types) showed greater diversity than female offending (with three identified types). For the males, each type of offending had a distinct age profile, but this was not evident with the females. A new definition of offending specialization is given, and is shown to increase for males as offenders grow older. A case study on one of the male offending types illustrates the potential for identifying pathways of crime.
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This paper discusses the development of a filter model for prioritizing possible links in dwelling burglary. The filters utilize the central aspects of crime scene information that is available and accessible to investigators in burglary, namely geo-spatial, temporal, behavioural, and dwelling information. The proposed filters were analysed using a sample of 215 dwelling burglaries committed by 43 serial burglars (i.e. 5 offences each) in order to determine the sequence in which the filters should be considered in prioritizing possible linked offences. The results indicated that the following order (i.e. better performance to worse performance) was most effective at linking offences, utilizing: (1) geo-spatial information, (2) temporal aspects, (3) behavioural information and, lastly, (4) dwelling characteristics. Specifically, the results indicated that offences in close proximity to one another should be given priority. Further, any offence occurring within a 28-day span before or after the index offence should be given priority. The paper argues that behavioural and dwelling characteristics are less effective for linking than geo-spatial and temporal information because the former two aspects are influenced significantly by situational and contextual cues on offender decision-making.
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The life-course approach to criminal career research has devoted a good deal of attention to the generality or specialization of offending behavior. Typically, extant research demonstrates versatility on the part of offenders, yet such findings could be attributable, at least in part, to time and measurement aggregation bias. This work uses a temporally disaggregated and individualized measure of diversity in offending to determine whether the previous findings of generality hold up to shifts in methodology. Using data from a sample of serious felons, results indicated that the magnitude of specialization is greater than in prior studies. Regression results indicated that certain demographic and local life-circumstance variables are related to the extent of diversity. Theoretical and methodological implications are identified and discussed.
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Sexual offending is on the political agenda but there has been little research focus on the four offence categories-indecent assault against a female, indecent assault against a male, indecency between males and unlawful sexual intercourse with a girl under 16-which together comprise the vast majority of convictions for sexual offences in England and Wales. We consider the criminal record (1963-94 inclusive) of the 6,097 males convicted of one of these offences in 1973. The results are discussed in terms of criminality, heterogeneity, dangerousness and specialization. By recognizing two levels of analysis-general crime level and sex crime level-we argue that sex offenders can be both generalists and specialists; they may range widely across a spectrum of offences but still specialize within sexual offending.
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The age-crime curve, increasing to a peak in the teenage years and then decreasing, is well-known. Less well-known is that it seems to reflect variations in prevalence (the proportion of persons who are offenders) rather than incidence (the rate of offending by offenders). Age-crime curves for individuals do not resemble the aggregate curve since incidence does not change consistently between the onset and the termination of criminal careers. This has major implications for criminal justice policy since the greatest residual length of criminal careers, and hence the greatest potential incapacitative effect, may be between ages thirty and forty, not at the peak age. Different types of offenses peak at different ages; this probably reflects crime switching rather than the replacement of one group of offenders by another. There is little specialization in offending, but specialization does increase with age. Age effects need to be separated from period and cohort effects. The age-crime curve probably reflect...
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This paper outlines a brief history of the evolutionary trajectory of offender profiling and illustrates the three broad strands (investigative, clinical, and statistical) that emerged in the 1970s–1990s. We then indicate how a more pragmatic, interdisciplinary practitioner–academic model has emerged in recent years and go on to describe the range of contributions that are now made across the criminal justice field. More recently termed ‘behavioural investigative advice’ in the UK, the paper then argues that whilst a range of potential contributions exist (from linking crimes, risk assessment, provision of bad character evidence, investigative interviewing advice, to geoprofiling), the nature of the process by which that contribution occurs is not yet well understood. The review of these potential contributions concludes with several suggestions and recommendations for further research and relevant methodologies by which to conduct that research. This includes the requirement to combine conceptual and theory-driven models alongside empirically driven statistical approaches, as well as the requirement to more precisely delineate and describe how contributions are made by behavioural experts through cognitive task analyses and associated methods.
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This paper considers a suspect prioritization technique and tests its validity using a sample of commercial armed robbery offences from St John's, Newfoundland, Canada. The proposed technique is empirically grounded in criminal careers and journey‐to‐crime research. Suspects with a previous criminal history are selected and ranked in ascending order by the distance they live from the location of the crime in question, with the nearest suspect given highest priority. Effectiveness is measured by the percentage of ranked suspects that needs to be searched before the offender is identified. Results show that 65% of the robbers were identified in the top 10% of ranked suspects. Limitations and proposed refinements are discussed in terms of future prioritization strategies and policing research.
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In this study, the process of burglars' specialisation was examined. 15 sub-categories of burglaries committed by 3,066 burglars were analysed, using a thematic approach. The result of an SSA-I showed that four themes existed in the structure of burglary: 'residential', 'commercial', 'public', and 'industrial/storage'. Also it was found that 'res- idential' and 'commercial' burglaries were the most distinct from each other, providing for two dominant foci for burglaries. The results of POSA also confirmed that most bur- glars specialised in either 'residential' or 'commercial' burglaries. Few were specialised in 'public' or 'industrial/storage' burglaries. In addition, the number of people who spe- cialised in commercial burglaries decreased with the increase of burgling experiences. The psychological processes underlying burglars' specialisation in one theme, or shift from one to another, are discussed. This study shows that the thematic approach offers a method of studying the multidimensional nature of burglars' psychological processes of specialisation.
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The age at which people begin to offend and the variety of different offenses that they commit while active have independently received a considerable amount of attention from researchers. However, there has been little attempt to connect these two relatively distinct lines of inquiry. Recently, two prominent criminological theories, Gottfredson and Hirschi's general theory of crime and Moffitt's taxonomy of offending behavior, have advanced formal theoretical models that include predictions about the relationship between onset age and offense versatility. The authors test the validity of these predictions using data from the second Philadelphia birth cohort study conducted by Tracy, Wolfgang, and Figlio. In support of the predictions from these theories, the authors find a relationship between onset age and offense versatility. More detailed analyses, however, show that this association vanishes after controlling for age. Thus, there was a tendency for offenders to become more specialized in their offending over time regardless of the age at which they initiated offending. The theoretical implications of this finding are discussed.
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In the absence of physical evidence, investigators must often rely on offence behaviours when determining whether several crimes are linked to a common offender. A variety of factors can potentially influence the degree to which accurate linking is possible, including the similarity coefficient used to assess across-crime similarity. The current study examines the performance of two similarity coefficients that have recently been compared to one another, Jaccard's coefficient (J) and the taxonomic similarity index (Δs), using samples of two crime types, serial homicide (N=237) and serial burglary (N=210). In contrast to previous research, the results indicate that Δs does not significantly outperform J with respect to linking accuracy. In addition, both coefficients lead to higher levels of linking accuracy in cases of serial homicide compared to serial burglary. Potential explanations for these findings are presented and their implications are discussed.
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This study examines the crime patterns of 76 New Zealand serial sexual offenders in order to determine the extent to which offenders display locational consistency in their choice of crime locations. More specifically, the hypothesis was that there would be intraseries consistency in the distances travelled (spatial consistency) and the characteristics of the crime sites selected (environmental consistency) by serial sexual offenders. For spatial consistency to be tested, the distances travelled from home to offend and the criminal range for each offence series were analysed. Support was found for spatial consistency, and, in line with much overseas research, it was also found that the offenders typically did not travel very far from home to offend (median distance of 3 km). The environmental consistency measure was made up of various physical, temporal, and contextual variables that described the environmental characteristics of an offence. As hypothesised, it was found that offenders displayed intraseries environmental consistency in offence site selection beyond the level of that expected by chance. The implications of this both for understanding offender spatial decision making and for geographical profiling are discussed. Copyright
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This study examines the criminal arrest records of a Danish birth cohort of 28,884 men to test the hypothesis that specialization exists for violent offending. Property offending is included for comparison. Specialization in violence is found to exist for offenders with more than three arrests, and specialization in property offending, for offenders with fewer than four arrests. Knowledge of past violent offending is discussed as a potentially valuable part of the predictive equation of future violence.
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The study of specialization in offending careers is relevant to the key theoretical issue of whether different types of offending reject only one underlying theoretical construct (such as delinquent tendency) or several different constructs. This research improves on previous studies of specialization in offending careers in three ways: (1) It is based on the complete juvenile court careers of a very large sample of offenders (nearly 70,000). (2) It uses a fine-grained classification of 21 offense types. (3) It uses a new measure of the strength of specialization, the Forward Specialization Coefficient (FSC). Both transition matrices and offending careers are studied. The major findings from the transition matrices are (1) there was a small but significant degree of specialization in offending superimposed on a great deal of versatility: (2) the degree of specialization tended to increase with successive referrals, and this was not due to more versatile offenders dropping out: and (3) the relative extent to which offenders specialized in different offenses held for two jurisdictions (Maricopa County, Arizona, and Utah), both sexes, and all ages. The analyses of offending careers showed that the most specialized offenses were runaway, burglary, motor vehicle theft, liquor violations, incorrigibility, curfew, truancy, and drugs. Nearly 20 percent of the offenders were identified as specialists. The conclusion is that, while offending was versatile to a first approximation, delinquency theories should attempt to explain specialization and specialists in order to yield more accurate quantitative predictions about offending careers.
Article
As we have tried to explain in this paper, we believe that the concept of a criminal career, the distinction between participation and frequency, and the longitudinal research method all have considerable value for criminological theory and policy. We have no particular stake in demonstrating that the individual frequency of offending stays constant over age; however, based on the present state of knowledge, it appears that participation in offending, but not frequency, varies with age. We are not uncritical enthusiasts of the concepts of career criminals and selective incapacitation, but we do believe that these policy ideas can stimulate important research. The outcome of the debate over these policies, however, has little relevance for the value of research on criminal careers, the participation/frequency distinction, and the longitudinal method - all of which rest on theoretical, methodological, and other scholarly considerations.
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A sample of serial stranger rape cases ( n = 43) that had occurred in Finland during the years 1983–2001 were studied with the objectives being to: (a) describe the characteristics of the offenders; (b) explore the structure of serial rape; and (c) demonstrate behavioural linkage through an analysis of the offenders' crime scene behaviour using both multidimensional scaling (MDS) and discriminant function analysis (DFA). The material was content analysed with regard to the occurrence of a number of dichotomous variables. The inter-relationships of the variables was studied using MDS. The analysis revealed two previously identified major modes of interaction with the victim: involvement and hostility. Employing MDS and DFA, it was shown that the offences of different offenders were distinguishable in terms of variation between the offences of different offenders and consistency within the offences of a single offender. Using DFA, the classification accuracy clearly exceeds that expected by chance, and 25.6% of the cases were classified without any error. The results are discussed in relation to their practical utility and previous studies. Copyright © 2005 John Wiley & Sons, Ltd.
Article
Offending specialization has received considerable attention in past research on criminal careers. Relatively little attention has been given to examining the relationships between various sub-group differences and the extent to which individuals tend toward specialization or versatility in their criminal careers. In the present analysis, we examine hypotheses derived from Moffitt's recent developmental theory that bear directly on offending specialization. Our analysis examines direct relationships between gender, onset age, persistence and offending specialization as well as the interaction of these influences and offending specialization. Our findings reveal results that are both consistent and inconsistent with Moffitt's dual taxonomy of offending behavior.
Article
Linkage analysis is a crucial part of the investigative process when faced with a possible series of related offences. Establishing behavioural consistency (i.e., offender's behaviours consistently present across the series) is at the core of linkage. Recent empirical studies have found little evidence of consistency looking at either individual or groups of behaviours in serial homicide. It is argued that behavioural changes are rooted in the changing cognitive strategies that offenders use to reach their ultimate goal (i.e. the commission of multiple homicides). Factors that could account for these changes include learning, situational factors, loss of control, and changes in the offender's fantasy. Patterns of behavioural change have been identified in serial crimes, such as rape. However, no empirical studies have looked at patterns of behavioural change in serial homicide. The present study examined patterns of consistency and change using a combination of thematic and behavioural subgroup approaches that use Multidimensional Scaling. Thematic differentiation indicative of behavioural manifestations of cognitive strategies was found in all three examined subgroups: planning, wounding, and offender–victim interaction, and patterns of change within these subgroups provided support for the above theories. Looking at behavioural patterns rather than individual behaviours, may be a more fruitful way of examining consistency in serial homicide, and could have significant implications for linkage analysis. Copyright © 2010 John Wiley & Sons, Ltd.
Article
Whilst case linkage is used with serious forms of serial crime (e.g. rape and murder), the potential exists for it to be used with volume crime. This study replicates and extends previous research on the behavioural linking of burglaries. One hundred and sixty solved residential burglaries were sampled from a British police force. From these, 80 linked crime pairs (committed by the same serial offender) and 80 unlinked crime pairs (committed by two different serial offenders) were created. Following the methodology used by previous researchers, the behavioural similarity, geographical proximity, and temporal proximity of linked crime pairs were compared with those of unlinked crime pairs. Geographical and temporal proximity possessed a high degree of predictive accuracy in distinguishing linked from unlinked pairs as assessed by logistic regression and receiver operating characteristic analyses. Comparatively, other traditional modus operandi behaviours showed less potential for linkage. Whilst personality psychology literature has suggested we might expect to find a relationship between temporal proximity and behavioural consistency, such a relationship was not observed. Copyright © 2010 John Wiley & Sons, Ltd.
Article
Specialization in violence is an important scientific and policy topic, and over the past several decades, many analysis techniques for studying specialization have emerged. Research in this area continues to be hampered, however, by remaining methodological problems. To overcome these problems, we propose a new method for studying specialization in violence based on an item-response theory measurement approach that is implemented through a multilevel regression model. Our approach defines specialization as an individual level latent variable, takes into account the inherent confounds between specialization and overall level of offending, and gauges specialization relative to the population base rates of each offense. Our method also enables researchers to 1) estimate the extent and statistical significance of specialization, 2) assess the stability of specialization over time, and 3) relate specialization to explanatory variables. Using data from three studies, we found substantial levels of specialization in violence, considerable stability in specialization over time, and several significant and relatively consistent relationships of specialization to explanatory variables such as gender, parental education, and risk-seeking.
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For both public policy and theoretical reasons, criminologists have been interested in the degree to which criminal offenders specialize in particular crimes. Traditionally, offense specialization has been measured with the forward specialization coefficient (FSC). Recently, the FSC has been criticized for being interpretationally obtuse and having no known sampling distribution. In this paper we examine both the interpretational and the statistical properties of the FSC. We conclude that (1) it has an intuitive interpretation that is no less useful than either a standard correlation coefficient or its competitors, (2) its sampling distribution is approximately normal, and (3) the conventional formula for the estimated standard error of the FSC may underestimate the true standard error in some circumstances. With these results behind us, we propose and illustrate both a parametric statistical test for the difference between two independent FSCs and two nonparametric alternatives.
Article
Offending specialization continues to be a subject of empirical inquiry for scholars interested in criminal careers. Early research consistently spoke to the generality of offending profiles, but more recent work has revealed somewhat mixed findings. These results have emerged alongside newly developed and applied methods that detect and describe offending specialization. To what extent these methods shape divergent conclusions and/or provide overlapping insight remains unclear, however. Therefore, the degree to which more recent inquiries are actually studying the same operational definition of specialization is unknown. In order to consider this issue further, this study utilizes four frequently applied approaches with a single data set. The study indicates when and where findings converge and also describes any unique insights provided by each method. The work concludes with a discussion surrounding the utility of applying multiple strategies in assessing specialization in criminal offending.
Article
A model of individual sexual offenders' spatial activity was developed based upon 45 British male sexual assaulters who had committed at least two assaults. For each offender a separate map was produced indicating the spatial locations of his offences and residence. A Marauder model and a Commuter model of offender's spatial behaviour was proposed. As an elaboration of the Marauder model, the Circle and Range hypotheses were tested against the sample of offenders. Results of the study support the Marauder model showing that most of the sample (87%) move out from their home base in a region around that base to carry out their attacks. The antithetical Commuter model was not supported within the sample. The Circle and Range hypotheses were supported demonstrating that offenders operate within a distinct offence region (in 91% of cases) and that the distance they travel to offend correlates directly with distances between offences (r = 0.93, p < 0.001). The findings clearly indicate that there is a basis for a model of offence venue choice by individuals within the sample. The present study supports the value of a theory of domocentricity within offenders' lives and offers potential applicability to the solving of crimes.
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Previous research has explored whether criminological theories can account for the apparently specialized behaviors of sexual offenders. One perspective proposes that criminals are versatile, engaging in an array of antisocial behaviors. The alternative perspective, more common in sexual offendi ng research, is that sexual offenders (especially child molesters) engage in sexual offenses exclusively or predominantly. This study examined 374 male sexual offenders referred for civil commitment. Offenders were compared by crime classification and level of specialization and were assessed on a selection of variables that measured general criminality and sexual deviance. Specialization level was a stronger group discriminator than offender classification. Versatile offenders were significantly more likely than specialist offenders to present with generic antisocial behaviors predicted by traditional criminology. Specialist offenders reported more indicators of sexual deviance than versatile offenders. The theoretical implications of these findings are discussed. Yes Yes
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