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Variability in Behavioural Consistency Across Temporal Phases in Stranger Sexual Offences
Abstract
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.
... Further some studies have calculated a similarity coefficient for each individual crime scene behavior (Deslauriers-Varin & Beauregard, 2014;Harbers et al., 2012). Studies that have compared the relative merit of including all crime scene behavior in one measurement of behavioral similarity to using domains or themes of behavior have concluded that predictions of crime linkage are more accurate when using all crime scene behaviors together (e.g., Bennell et al., 2009;Oziel et al., 2015). ...
... In 2018, Davies, Woodhams, and Rainbow summarised the findings for studies of serial sexual offending that have investigated the relative behavioral similarity seen for same-offender and different-offender crime pairs. They noted that these studies (Bennell et al., 2009;Oziel et al., 2015;Slater et al., 2015;Woodhams & Komarzynska, 2014;Woodhams & Labuschagne, 2012) have been conducted using samples from the United Kingdom, Canada, and South Africa. In all studies, same-offender crime pairs were characterised by significantly greater similarity in crime scene behavior than different-offender crime pairs. ...
... It can range from 0.00 to 1.00 and 0.70 represents an adequate level of accuracy (Hosmer & Lemeshow, 2002). Several of the studies referenced here have used this statistical measure and the values found range from 0.75-0.99 2 (Bennell et al., 2009;Davidson & Petherick, 2020;Oziel et al., 2015;Slater et al., 2015;Tonkin et al., 2017;Woodhams & Komarzynska, 2014;Woodhams & Labuschagne, 2012;Woodhams et al., 2019;Yokota et al., 2015;2017a;2017b) with most studies reporting AUCs in excess of 0.80, an excellent level of discrimination accuracy (Hosmer & Lemeshow, 2002). ...
Crime linkage can be a useful tool in the investigation of sexual offenses when other, physical evidence is unavailable or too costly to process. It involves identifying behavior that is both consistent and distinctive, and thus forms an identifiable pattern through which a series of offenses committed by the same offender can be distinguished. While there is a substantial body of research to support the principles of crime linkage, samples often contain only one type of sexual offense, and further research is needed into offenses such as voyeurism and exhibitionism. In practice, there are a number of ways in which crime linkage can be conducted, and a variety of terms are used to describe these different processes. While writings from practitioners provide insight into how crime linkage is conducted, research now needs to focus more on systematically mapping its practice and documenting procedural differences. There are also a number of additional considerations that require further research attention where the practice of crime linkage is concerned, such as the utility of computerised databases designed to assist with the process, the human decision-making element of linking and how bias can affect this, and the effects of expertise and training on linkage efficacy.
... Las conductas de los agresores sexuales en la escena del crimen pueden verse afectadas por factores situacionales, o de carácter contextual (Oziel, Goodwill & Beauregard, 2015;Goodwill, Lehmann, Beauregard & Andrei, 2016), pues el delito debe ser analizado al menos en dos niveles para comprenderlo: el individual y el socioambiental (Janosch & Soto, 2018). Con la denominación de factores situacionales nos referimos a elementos tales como la intensidad de la resistencia que ofrece la víctima (Salfati, Horning, Sorochinski & Labuschagne, 2015), determinadas condiciones ambientales inesperadas, el tiempo que dura la agresión, el lugar en el que se comete o bien la posible aparición de testigos y/o policías, pueden provocar un cambio en las conductas del delincuente, alterando el MO planificado (Wikström, 2006;2014). ...
... 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). ...
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.
... Las conductas de los agresores sexuales en la escena del crimen pueden verse afectadas por factores situacionales, o de carácter contextual (Oziel, Goodwill & Beauregard, 2015;Goodwill, Lehmann, Beauregard & Andrei, 2016), pues el delito debe ser analizado al menos en dos niveles para comprenderlo: el individual y el socioambiental (Janosch & Soto, 2018). Con la denominación de factores situacionales nos referimos a elementos tales como la intensidad de la resistencia que ofrece la víctima (Salfati, Horning, Sorochinski & Labuschagne, 2015), determinadas condiciones ambientales inesperadas, el tiempo que dura la agresión, el lugar en el que se comete o bien la posible aparición de testigos y/o policías, pueden provocar un cambio en las conductas del delincuente, alterando el MO planificado (Wikström, 2006;2014). ...
... 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). ...
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.
... The third temporal variable was the amount of time the offender spent with the victim at the scene (0 = 30 min or less; 1 = more than 30 min). Based on a past study by Oziel, Goodwill, and Beauregard (2015), a short period of time was categorized as 30 min or less and a high period of time was more than 30 min spent with the offender. It is generally thought that committing a rape at the victim's home is beneficial because of the lack of witnesses and thus one could hypothesize that offenders may be willing to spend a longer amount of time with the victim at the scene of the crime when in a private location that minimizes the risk of witnesses. ...
... A victim was more likely to be encountered, assaulted and released in their home when the offender spent a shorter amount of time at the crime scene. A "short" amount of time was operationalised as 30 min or less (based on past research by Oziel et al., 2015). Home-intruder sex offenders were more likely to spend 30 min or less with their victims compared with others. ...
One particular crime location in sexual assaults is the victim’s residence. Similar to sexual burglars, “home-intruder” sex offenders choose to assault the victim in her residence, most likely in their bedroom. The aim of the current study is to analyze modus operandi, temporal factors, and victim characteristics in a sample of 347 stranger sexual assaults committed by 69 serial sex offenders to determine which factors may be more relevant to sexual assaults committed in the victim’s residence compared with sexual assaults committed at another type of location. Our hypothesis is that offenders who choose to sexually assault victims in their home constitute a specific type of sex offender, one that resembles the sexual burglar. Results showed that modus operandi (e.g., burglary), temporal factors (e.g., time at crime scene with victim), and victim characteristics (e.g., age, victim-offender relationship) were significant in predicting whether the victim encounter, crime site, and victim release site were located at the victim’s residence or not. Moreover, these findings were generally significant across the three crime locations, which can be explained by the high consistency in location during home-intrusion sexual assaults. Situational crime prevention strategies aimed at making a residence less attractive for offenders should help reducing this particular type of sexual assault.
... Various elements of an offender's crime scene that relate to the method of attack have been identified as salient features of the offender's modus operandi (Oziel, Goodwill & Beauregard, 2015). Victim injury and the sexual acts committed are the types of behaviors that may reflect an offenders underlying propensities and, therefore, likely to be observed more consistently in an offender's offence behavior (Oziel et al., 2015). ...
... Various elements of an offender's crime scene that relate to the method of attack have been identified as salient features of the offender's modus operandi (Oziel, Goodwill & Beauregard, 2015). Victim injury and the sexual acts committed are the types of behaviors that may reflect an offenders underlying propensities and, therefore, likely to be observed more consistently in an offender's offence behavior (Oziel et al., 2015). ...
Purpose The research reported in this article tests the General Theory of Crime using a sample of repeat sex offenders. Methods Logistic regression analyses were conducted on a sample of 69 repeat sex offenders interviewed while incarcerated in a Canadian penitentiary. Results Findings show support for the General Theory of Crime. The current analyses found low self-control to be a significant predictor of offence behaviors that correspond closely to elements of the personality trait identified in the General Theory of Crime. Sexual offenders lower in self-control exhibited behaviors during various stages of the sexual offence that were impulsive, risky, insensitive, short-sighted, physical, and aggressive, all of which correspond to the theoretically defined personality trait of low self-control. Conclusions As a point of theoretical extension, we propose that future studies consider self-control in a situational manner. Moreover, the study questions the relative stability of low self-control during the entire criminal event.
... The first issue is difficult to prove or disprove as evidence is often in the eye of the beholder (see Dern, Dern, Horn, & Horn, 2009) and in fast-developing areas of research the extent of the evidence is often difficult to distil (see Alison et al., 2010). As for the second issue, behavioural investigative research has shown that offence behaviour, although influenced by Situation 9 Person interactions, is still relatively stable across crimes (Harbers, Deslauriers-Varin, Beauregard, & Kemp, 2012;Oziel, Goodwill, & Beauregard, 2014). However, the various situations within an offence confront an offender with a multitude of decisions to be considered (e.g., . ...
... These data sample appear in a number of publications to date Oziel et al., 2014). Of particular note is the correspondence of the approach cluster structure found in the current study and that found in the script analysis study conducted by using the same data sample. ...
PurposeContinued debate surrounds whether or not offender profiling is a valid practice. Critics have mainly contended that few studies have produced clear, quantifiable, evidence of a link between crime scene actions (A) and offender characteristics (C). Arguing that this is due to a failure to study offender actions as part of a dynamic decision-making process, this study sought to identify action phases that are representative of the general decisions an offender must make during the commission of a sexual offence, and relate these decisions to known characteristics of the offender (C).Methods
Two-step cluster analyses were performed on data from 347 stranger sexual offences, committed by 69 serial sexual offenders, by action phase: (1) search; (2) selection; (3) approach; (4) assault; and also for an offender's (5) characteristics. Multiple correspondence analysis (MCA) was then utilized to investigate the inter-relationship of action phase clusters and offender characteristics.ResultsThe MCA results indicated that specific behavioural macro-clusters formed across the various actions phase and offender characteristic clusters in a meaningful way. Additionally, the macro-clusters themselves corresponded to the extant literature on sexual assault, revealing several points of congruence between offender crime scene actions and offender characteristics.Conclusion
The results of the study demonstrate that when crime scene behaviours are interpreted within a dynamic decision-making process (i.e., utilizing action phases), reliable and valid empirical links may potentially be drawn between an offenders behavioural actions and their characteristics.
... BCL has been shown to be viable across a variety of crime types, in samples from all over the world: the United Kingdom, the United States, Canada, Finland, South Africa, Japan, Italy and Australia. These studies include rape (Santtila, Junkkila, & Sandnabba, 2005;Yokota, Fujita, Watanabe, Yoshimoto, & Wachi, 2007;Woodhams & Labuschagne, 2012;Winter, Lemeire, Meganck, Geboers, Rossi, & Mokros, 2013;Slater, Woodhams, & Hamilton-Giachritsis, 2015;Oziel, Goodwill, Beauregard, 2015;Sorochinski & Salfati, 2018;Woodhams et al., 2019;Davidson & Petherick, 2020), robbery (Woodhams & Toye, 2007;Burrell, Bull, & Bond, 2012), and also volume-and property crime: arson (Santtila, Fritzon, & Tamelander, 2004), burglary (Bennell & Canter, 2002;Benell & Jones, 2005;Tonkin, Santtila, & Bull, 2012;Bouhana, Johnson, & Porter, 2016), and car theft (Tonkin, Grant, & Bond, 2008;Davies, Tonkin, Bull, & Bond, 2012). ...
Behavioural crime linking refers to the practice of trying to tie two or more offences to the same offender using behaviour observable at the crime scene. It rests on the assumptions that offenders behave consistently enough from one offence to another, and distinctively enough from other offenders allowing offences to be successfully linked together. Conceptualised in the 70s, and developed methodologically with increased scientific rigour from the 90s, the last decade has seen a sharp rise in published studies on behavioural crime linking. From empirical validation of the underlying assumptions to mapping out practice and more ecologically valid tests of linkage accuracy, the field has developed considerably. Considering that investigating homicide is resource intensive, not to mention serial homicide, reliable and valid behavioural crime linking has the potential to aid and prioritise investigative avenues and help solve serial homicide.
Most studies on serial homicide have been carried out on North American samples. While some research has studied the consistency and distinctiveness of serial homicide offenders, few have empirically tested models of behavioural crime linking and linkage accuracy with serial homicide. Another shortcoming in behavioural crime linking research is the use of mostly serial cases to model crime linking, even though real crime databases include both serial and one-off offences. Some studies have tested the effect of added one-offs on the linkage accuracy of burglary and rape, but none so far the effect this would have on homicide. Additionally, while some studies have compared serial homicide offences to one-off homicides, none have tested whether it would be possible to predict whether a homicide belongs to a series or is a singular offence. Cognitive bias, especially confirmation bias or the expectancy effect, has been shown to have a considerable effect on crime investigation. No studies to date have explored the effect of such bias in behavioural crime linking.
The general aim of the thesis was to increase ecological validity of behavioural crime linking research, especially with regard to sampling choices and analyses that strive to answer questions relevant for homicide investigation. The main sample consisted of 116 Italian serial homicides, committed in 23 separate series of homicide. Additionally, information about 45 cases of hard-to-solve one-off homicide was gathered, coded, and added to the sample. Study I found seven behavioural dimensions of offending (e.g., sexually motivated homicides and aspects of control-behaviour) in line with previous research. Notably, also other motives than sexual were found in the killings. A majority of offences (63%) were correctly classified to their actual series in the predictive part of the study. Study II was an experiment that investigated whether knowledge of series membership increased perceived (coded) behavioural similarity in homicides committed by the same offender. While no support was found for a strong expectancy effect, the experimental task may have lacked in sufficient complexity, and replication is thus needed. Study III found several key differences between serial and singular homicides and was able to successfully use these differences to predict with good accuracy whether an offence was part of a series. Study IV combined all the advances in the methodology thus far and showed that behavioural crime linking was still viable even with a large proportion (10:1) of one-off homicides added into the sample. As a function of added one-off homicides, the specificity of the model worsened (more false positives), as did the proportion of offences belonging to a series found near the top of a ranked listing from more behaviourally similar to less behaviourally similar. Overall model accuracy remained good, though, further validating the practice of behavioural crime linking with more ecologically valid data.
The studies of the present thesis contribute to the methodology of behavioural crime linking research. Replication on local crime databases is needed to maximise the practical usefulness of the models in different jurisdictions. Going forward, a close-knit collaboration between researchers and practitioners is called for, to keep the research relevant for practice and to develop evidence-based practice. As we gain a clearer picture of the accuracy and error rate of behavioural crime linking models, their usefulness increase in both the criminal investigative phase and in the trial phase with behavioural crime linking being presented as expert evidence.
... The victim not knowing the offender reduces the clear-up rate considerably (Corovic, Christianson, & Bergman, 2012). The reason is the limited information available at the start of the investigation which comes from the victim or the crime scene (Oziel, Goodwill, & Beauregard, 2015;ter Beek, van den Eshof, & Mali, 2010). Therefore, depending on the existence or not of a relationship between the offender and the victim and, according to information from the US, sexual offenders of adult women are divided into two large categories: (1) the offenders who know the victim because they had a prior relationship (partners, family or just knew each other), and (2) offenders who did not know their victim. ...
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.
... Therefore, we cannot quite compare their results to those of the current study. The same is the case for Oziel, Goodwill, and Beauregard (2014) and Hewitt and Beauregard (2014). Another variable that will be tested in this study is victim-offender relationship. ...
... If there were discrepancies between interview data and police reports, the evidence contained in the police report was used. These data sample appear in a number of publications to date (Beauregard, Proulx, et al., 2007; Beauregard, Rossmo, et al., 2007; Oziel et al., 2014). Of particular note is the correspondence of the approach cluster structure found in the current study and that found in the script analysis study conducted by Beauregard, Proulx, et al. (2007) using the same data sample. ...
The current study explores the way guardianship is perceived by offenders and the extent to which it affects the likelihood of disruption in sexual offences against adult females. Specifically, we compare the micro-situational contexts in which sexual offences against adult females are disrupted to those in which these offences are completed. Data on sexual crime events was collected from 138 adult males who were incarcerated for committing a sexual offence against a woman using a self-report questionnaire incorporating a crime-script framework. We found that the presence or availability of a guardian does not guarantee offence disruption. Rather, action taken by the guardian is the critical factor which determines a sexual offender’s decision to cease the offence.
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).
Criminal behavioral profiling as an investigative aid used to solve complex, violent crimes has been a topic of much interest and debate since the early 1980s. Criminal behavioral profiling theory posits that criminal offense behavior is a manifestation of the personality of the criminal and that analysis of those crime behaviors describes major personality traits and characteristics of the offender as well as the motivation for the crime. However, many question profiling theory because of its lack of empiricism. Assuming that behavior reveals motivation, the Federal Bureau of Investigation (FBI) developed an untested motive-based typology to analyze and profile serial arson crimes. This study addressed the problem of the relationship, if any, between arson motive and arson behavior and to what extent arson behavior can predict arson motive in order to test a fundamental premise of arson profiling. The purpose of this quantitative correlational study was to explore the relationships between the criterion variable of five motives for arson and the predictor variables of 19 arson behaviors to test the validity of the basic assumptions of criminal profiling of serial arson crimes. The study used secondary archival data previously obtained by the Federal Bureau of Investigation from a non-random convenience sample of 83 convicted and incarcerated serial arson offenders. The data was analyzed using descriptive and nonparametric inferential tests including Pearson’s chi-square test of independence (Fisher’s exact test and Phi) and loglinear analysis. Only two significant associations were found between the criterion variable arson motives and the arson behaviors, those being profit motivation and communication with the victim, χ2 (1) = 14.850, p < .01, and between crime concealment motivation and items removed from the scene, χ2 (1) = 11.195, p < .009. Small sample size and missing or low frequencies caused low power, and significant associations were found for only 2% of the variables compared. The study results suggested the FBI’s motive-based model cannot be statistically supported by their data. Future research should continue to focus on relationships between arson offense behavior and motivation while controlling for situational mediators and moderators.
The extrapolation of characteristics of criminals from information about their crimes, as an aid to police investigation, is the essence of ‘profiling'. This paper proposes that for such extrapolations to be more than educated guesses they must be based upon knowledge of (1) coherent consistencies in criminal behaviour and (2) the relationship those behavioural consistencies have to aspects of an offender available to the police in an investigation. Hypotheses concerning behavioural consistencies are drawn from the diverse literature on sexual offences and a study is described of 66 sexual assaults committed by 27 offenders against strangers. Multivariate statistical analyses of these assaults support a five-component system of rapist behaviour, reflecting modes of interaction with the victim as a sexual object. The potential this provides for an eclectic theoretical basis to offender profiling is discussed.
The article presents and develops a paradigm of serial, sexual offenders derived from our criminal investigative analysis experience and research. The paradigm delineates two major categories of sexually violent offenders. The Impulsive Offender is described as being criminally unsophisticated, and largely reactive in terms of his victim selection and crime-scene behavior. It is observed that this type of offender is often characterized by a diverse criminal history, rather generic sexual interests, and significant levels of physical violence. The Ritualistic Offender, in contrast, is characterized by diverse paraphilic interests, a pervasive and defining fantasy life, and a carefully developed and executed set of crime-scene behaviors. These two distinctions are examined as they inform the analysis of a sexually violent crime by criminal investigative analysts as well as the clinical evaluation of these offenders within a forensic context. The potential utility of this type of paradigmatic delineation for risk assessments and for assessing the potential for future recidivism is also highlighted.
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.
Most approaches to offender profiling depend on a naïve trait perspective, in which the task of predicting personality characteristics from crime scene actions relies on a model that is nomothetic, deterministic, and nonsituationist. These approaches rest on two basic premises: behavioral consistency across offenses and stable relationships between configurations of offense behaviors and background characteristics. Research supports the former premise but not the latter. Contemporary trait psychology reveals that this is probably due to the fact that Person X Situation interactions have an effect on offense behavior. When profiling reports rely on a nalve trait approach, such reports should be used with caution in criminal investigations and not at all as evidence in court until research demonstrates its predictive validity. (PsycINFO Database Record (c) 2012 APA, all rights reserved)
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.
A sample of stranger rape offences (n = 271) registered in the Dutch Violence Crime Linkage Analysis System database in the Netherlands between 1997 and 2007 was studied with the objective of developing statistical models, which give an indication of the probability of basic offender characteristics. Observable crime characteristics concerning the modus operandi, interaction between the offender and the victim, violence, precautionary measures, and sexual behaviours were selected in the dataset. Offender characteristics were selected based on their usefulness for the police organisation in narrowing the scope of a criminal investigation. Spatial behaviour, criminal history, and living situation of the offender were selected. From the predictive models, four out of five achieved a correct rate of over 70%, and all models predicted better than the best guess method. The proposed models for distance and prior convictions for violence seem particularly promising. Both these models show an improvement of correctly predicted offender characteristics of more than 20 percentile points compared with that which could have been estimated based on the average in the total sample. The predictive value of the models needs to be tested further with ‘new offences’, which were not used to construct the model. In general, the current study supports the finding that crime characteristics can be used to get an indication of the probability of certain offender characteristics. Nevertheless, for an understanding of the relationship between the crime characteristics and offender characteristics, a further development of a theoretical framework is urgently necessary. Copyright © 2009 John Wiley & Sons, Ltd.
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.
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.
Purpose. Through an examination of serial rape data, the current article presents arguments supporting the use of receiver operating characteristic (ROC) analysis over traditional methods in addressing challenges that arise when attempting to link serial crimes. Primarily, these arguments centre on the fact that traditional linking methods do not take into account how linking accuracy will vary as a function of the threshold used for determining when two crimes are similar enough to be considered linked.Methods. Considered for analysis were 27 crime scene behaviours exhibited in 126 rapes, which were committed by 42 perpetrators. Similarity scores were derived for every possible crime pair in the sample. These measures of similarity were then subjected to ROC analysis in order to (1) determine threshold-independent measures of linking accuracy and (2) set appropriate decision thresholds for linking purposes.Results. By providing a measure of linking accuracy that is not biased by threshold placement, the analysis confirmed that it is possible to link crimes at a level that significantly exceeds chance (AUC = .75). The use of ROC analysis also allowed for the identification of decision thresholds that resulted in the desired balance between various linking outcomes (e.g. hits and false alarms).Conclusions. ROC analysis is exclusive in its ability to circumvent the limitations of threshold-specific results yielded from traditional approaches to linkage analysis. Moreover, results of the current analysis provide a basis for challenging common assumptions underlying the linking task.
Criminal profiling is an investigative tool that has attained unprecedented recognition despite a clear lack of empirical
criminological evidence supporting its validity and assumptions. The ‘‘homology hypothesis’’ is one of these assumptions,
and it postulates a direct relationship between crime scene characteristics and personal attributes of the offender. Few studies
were able to test empirically such a relationship while taking into account opportunity factors. Thus, the aim of this study
is to compare the role of both stable individual characteristics and opportunity factors in explaining crime scene behaviors
of sexual aggressors of women. Sequential logistic regression analysis was performed on a sample of 187 adult males convicted
of at least one sexual offense against a female of at least 16 years of age. The results revealed that opportunity factors
were more important in explaining crime scene behaviors of sex offenders as compared with criminal propensity factors. Results
are then discussed in light of the assumptions of criminal profiling and how they can be used in the criminal investigative
process.
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
The article presents and develops a paradigm of serial, sexual offenders derived from our criminal investigative analysis experience and research. The paradigm delineates two major categories of sexually violent offenders. The Impulsive Offender is described as being criminally unsophisticated, and largely reactive in terms of his victim selection and crime-scene behavior. It is observed that this type of offender is often characterized by a diverse criminal history, rather generic sexual interests, and significant levels of physical violence. The Ritualistic Offender, in contrast, is characterized by diverse paraphilic interests, a pervasive and defining fantasy life, and a carefully developed and executed set of crime-scene behaviors. These two distinctions are examined as they inform the analysis of a sexually violent crime by criminal investigative analysts as well as the clinical evaluation of these offenders within a forensic context. The potential utility of this type of paradigmatic delineation for risk assessments and for assessing the potential for future recidivism is also highlighted.
In a recent study of personal robbery, commissioned by the Home Office in the UK, a qualitative typology of robbery offences was proposed based on the approach used by the offender to commit the crime, consisting of four approach types: Blitz, Confrontation, Con, and Snatch. Conceptual inspection of the typology reveals that these proposed types may be hypothetically demarcated as the product of two latent dimensions: interaction (between the offender and the victim) and violence (used to threaten/harm the victim). The current paper utilises crime scene information from 72 incarcerated male offenders convicted of ‘street’ robbery to test this hypothesis. Convergent statistical analysis was utilised to test the structure of Smith's typology first using multidimensional scaling (MDS) and then principal component analysis (PCA). MDS and PCA analyses provided convergent support for the existence of the four robbery styles and the latent dimensions of interaction and violence. Implications of Smith's typological structure and latent behavioural dimensions on the conceptualisation and classification of robbery offences are discussed within the existing literature on ‘street’ robbery. Copyright © 2012 John Wiley & Sons, Ltd.
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
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.
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.
In A General Theory of Crime, Gottfredson and Hirschi propose that low self-control, in interaction with criminal opportunity, is the major cause of crime. The research reported in this article attempts to test this argument while closely following the nominal definitions presented by Gottfredson and Hirschi. A factor analysis of items designed to measure low self-control is consistent with their contention that the trait is unidimensional. Further, the proposed interaction effect is found for self-reported acts of both fraud and force (their definition of crime). Inconsistent with the theory are (a) the finding that criminal opportunity has a significant main effect, beyond its interaction with low self-control, on self-reported crime and (b) the substantial proportion of variance in crime left unexplained by the theoretical variables. Suggestions are offered for modifying and expanding the theory.
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.
This article examines the self-reported target techniques of 61 sexual offenders incarcerated in a maximum custody prison. Respondents were interviewed using a methodology employing other convicted felons as interviewers. The data lend support to a rational choice perspective revealing predatory rapists as decision makers since they largely attack females whom they perceive as vulnerable. In light of these findings, research is needed curbing fallacies leading to victim vulnerability.
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.
International research has suggested that rapist criminal histories can be predicted from certain offence behaviours. Ninety-six solved stranger rape cases were examined to determine if there was consistency in a New Zealand sample. Rapist behaviours during the offence were compared with criminal convictions prior to the rape. The primary statistical technique used was likelihood ratio stepwise binary logistic regression. Predictive utility of the results was limited, due to significant correlation coefficients between the criminal history variables. Nevertheless, the current study reflected the general findings of similar descriptive international research. These outcomes were: the majority of stranger rapists had prior criminal convictions, and the majority of those convictions were for property offences not sexual offending. Furthermore, ethnic minorities were over-represented among the offenders, and the majority of stranger rapists started committing their first known rapes in their mid- to late 20s. Finally, methodological difficulties were encountered during this study. This highlights the need to refine existing statistical approaches to predictive offender-based research.
Both theoretical and empirical studies of decision making in target selection have shown
that this process is highly dependent on the physical environment. However, research
specifi cally investigating decision making in sex offenders’ target selection is scarce. The
aims of the current study were to (1) identify target selection patterns in a mixed sample
of 78 Canadian and Portuguese adult rapists, (2) investigate how geographical decision
making infl uences target selection patterns, and (3) test the infl uence of the type of environment
on target selection patterns. The results indicate that Canadian and Portuguese
rapists exhibit different target selection patterns but that their geographical decision
making is congruent and consistent with the environment within which they operate.
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
The crime scene actions employed by offenders in stranger rapes were analysed in relation to offender characteristics. Data were drawn from an official police database and consisted of stranger rapes occurring in Finland between 1992 and 2001 (n = 100). The structure of dichotomous variables derived through a content analysis of crime scene actions and offender characteristics were analysed with non-metric multidimensional scaling (MDS). The first analysis revealed three separate action themes, with thematic emphases on Hostility, Involvement or Theft. The MDS-solution for offender characteristics suggested four themes: Conventional; Psychiatric/Elderly; Criminal/Violent; and Criminal/Property. Each case was assigned to one of the themes or as a hybrid in order to analyse the associations between action themes and characteristics. The only significant association was found between the action theme, Theft and characteristics theme Criminal/Property. The results are discussed in relation to previous research. Copyright © 2004 John Wiley & Sons, Ltd.
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.
Research on sex offenders has mainly guided clinical practice for risk assessment and therapeutic intervention. However, the current scientific knowledge on these offenders and their crimes is, in many aspects, of great importance to criminal investigations. Consequently, there is a need to build bridges between investigative psychology and the research being conducted on sex offenders. Four areas of research on sex offenders that have clear implications to investigative psychology can be identified: (1) the consistency or ‘crime-switching’ patterns of sex offenders; (2) the recidivism patterns of different types of sex offenders; (3) the police response to specific victim characteristics; and (4) the A → C equation of sexual assaults. This paper argues for a need to establish a dialogue between these two fields of research so that knowledge about sex offenders keeps growing whilst being able to inform policing practices in investigative psychology. Copyright © 2009 John Wiley & Sons, Ltd.
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.
Purpose. Conventional approaches to offender profiling assume a homology of the characteristics of offenders with their crime scene actions: the more similar two offenders are with respect to background characteristics, the higher the resemblance in their crime scene behaviour. This implicit working hypothesis is tested empirically.Methods. The study is based on a sample of 100 British male stranger rapists. These individuals were indexed with respect to the similarity in their crime scene actions as derived from witness statements. They were then compared with respect to their socio-demographic features and criminal histories as derived from police records. In a correlational analysis, we tested whether increased similarity in one domain (offence behaviour) coincided with higher resemblance in the other domains (socio-demographic features and previous convictions).Results. There is no positive linear relationship for any of the comparisons, i.e. rapists who offend in a similar fashion are not more similar with respect to age, socio-demographic features (such as employment situation and ethnicity) or their criminal records.Conclusions. These findings indicate no evidence for the assumption of a homology between crime scene actions and background characteristics for the rapists in the sample. We argue that this result suggests that the homology assumption is too simplistic to provide a basis for offender profiling. Implications for future research include the search for a suitable framework for offender profiling that is grounded in personality psychology. Further, methodological considerations are discussed, such as the potential application of probabilistic scales.
Receiver operating characteristic (ROC) analysis is a widely used and accepted method for improving decision making performance across a range of diagnostic settings. The goal of this paper is to demonstrate how ROC analysis can be used to improve the quality of decisions made routinely in a policing context. To begin, I discuss the general principles underlying the ROC approach and demonstrate how one can conduct the analysis. Several practical applications of ROC analysis are then presented by drawing on a number of policing tasks where the procedure has been used already (bite mark identification and linking serial crimes) or where it could be used in the future (statement validity assessment and determining the veracity of suicide notes). I conclude by considering briefly some of the potential difficulties that may be encountered when using ROC analysis in the policing context and offer some possible solutions to these problems. Copyright © 2005 John Wiley & Sons, Ltd.
Debate continues with regard to the possibility of inferring an offender's characteristic features from crime scene details (the process of so-called “offender profiling”). We argue that psychology generally has benefited from appreciating context in predicting behavior. In the same way, profiling would benefit from an appreciation of context in predicting characteristics. This “reverse” process is contingent on various “if…then” relationships. As one example, this paper demonstrates how profiling offender age from victim age is contingent on (i) the level of planning and (ii) the level of aggression displayed during the offense. Eighty-five stranger rape case records formed the data set. Moderated regression analysis revealed that victim age is a significant predictor of offender age only in cases where the offender has (i) shown evidence of planning the attack and/or (ii) acts in a gratuitously aggressive manner. The theoretical bases for these findings may lie in the extent to which offenders disparately plan and target victims and how extreme aggressiveness in stranger rapes may relate to a near-peer proxy for an offender's anger. The implications of the results for the processes and methods involved in offender profiling suggest that certain crime scene factors can have differential moderating effects on predictive outcomes. Copyright © 2007 John Wiley & Sons, Ltd.
Purpose. The psychological hypotheses that form the foundations for ‘Offender Profiling’ are identified and the research that has tested them is reviewed. Argument. ‘Offender profiling’ is taken to be the derivation of inferences about acriminal from aspects of the crime(s) he or she has committed. For this process to move beyond deduction based on personal opinion and anecdote to an empirically based science, a number of aspects of criminal activity need to be distinguished and examined. The notion of a hierarchy of criminal differentiation is introduced to highlight the need to search for consistencies and variations at many levels of that hierarchy. However, current research indicates that the key distinctions are those that differentiate, within classes of crime, between offences and between offenders. This also leads to the hypothesis ofa circular ordering of criminal actions, analogous to the colour circle, a ‘radex’. The radex model, tested using Multi-Dimensional Scaling (MDS) procedures, allows specific hypotheses to be developed about important constituents of criminal differentiation: Salience. MDS analyses reveal the importance of the frequency of criminal actions as the basis on which the significance of those actions can be established. Models of differentiation. The research reviewed mainly supports distinctions between criminals in terms of the forms of their transactions with their explicit or implicit victims. Consistency. Offenders have been shown to exhibit similar patterns of action on different occasions. The most reliable examples of this currently are in studies of the spatial behaviour of criminals. Inference. Under limited conditions it is possible to show associations between the characteristics of offenders and the thematic focus of their crimes. In general these results provide support for models of thematic consistency that link the dominant themes in an offender's crimes to characteristic aspects of his or her lifestyle and offending history. Implications. Much of what passes for ‘offender profiling’ in practice and as reported in the factual and fictional media has no basis in empirical research. However, there are some promising results emerging in some areas of study. These results are most likely to be of value to police investigations when incorporated into decision support systems and the training of police officers. The results doalso provide new insights into the psychology o crime.
Purpose Although rational choice researchers has investigated how offenders successfully commit certain crimes, there is a lack of research looking at the factors explaining the use - or not - of certain detection avoidance strategies. This study introduces the concept of "forensic awareness" as a detection avoidance strategy, and proposes to examine the effect of disinhibitors, target selection behaviors, and acts that may potentially leave evidence at the crime scene on its use.Methods Factors influencing forensic awareness are tested using logistic regression models on a sample of 222 rape events collected from offenders incarcerated in Canada.Results Offenders exhibit less forensic awareness when under the influence of drugs and/or alcohol. However, offenders who show some form of target selection are more likely to take forensic precautions. Finally, offenders who break and enter in the victim's residence, and undertake specific sexual acts during the crime are also more likely to exhibit forensic awareness.Conclusion Despite the increasing use and knowledge of forensic evidence by law enforcement, offenders are inconsistent in their forensic awareness and they direct most of their efforts toward protecting their identity, neglecting to either destroy or clean up DNA that could be recovered at the crime scene.
A rational choice theory approach was used to analyze the offense behavior of serial sex offenders. Qualitative data were
obtained through the descriptions of the crimes provided by 69 serial sex offenders who were incarcerated in a Correctional
Service of Canada institution. Based on the offenders’ accounts, a descriptive model specific to the hunting process was identified.
This model contained the following nine phases: offender and victim routine activities, choice of hunting ground, victim selection,
method of approach, attack location choice, method to bring the victim to the crime site, crime location choice, method to
commit the crime, and the victim release location choice. The model is discussed according to existing research on serial
sex offenders and environmental criminology. Implications for clinical practice, crime prevention, offender profiling, and
future studies are discussed.
Based on a sample of 682 male sex offenders, this study investigated variables of the offending behavior for predicting sexual recidivism in different age groups. The sex offenders were allocated into four age groups. For each group, those characteristics of offending behavior showing a significant bivariate correlation with sexual recidivism were extracted. Using logistic regression, we then analyzed their incremental validity above and beyond a previously developed Crime Scene Behavior Risk (CBR)-Score, which measures the risk of sexual recidivism without taking into account the offenders' age (Dahle, Biedermann, Gallasch-Nemitz, & Janka, 2010). Age-specific offending behavior variables with incremental validity were combined with the general CBR-Score into age-specific scores and examined for their predictive accuracy. We also analyzed the extent in which these age-specific scores showed incremental validity above and beyond the Static-99 (Hanson & Thornton, 1999). For three of the four age groups, age-specific Crime Scene Behavior Risk-Scores could be determined which were incrementally valid above and beyond the Static-99. Predictive accuracy varied between AUC=.74 and AUC=.90 (r=.28 to r=.49) depending on age group. The results are discussed within context of recent findings on the latent dimensions of actuarial risk assessment variables.
Jaccard has been the choice similarity metric in ecology and forensic psychology for comparison of sites or offences, by species or behaviour. This paper applies a more powerful hierarchical measure - taxonomic similarity (s), recently developed in marine ecology - to the task of behaviourally linking serial crime. Forensic case linkage attempts to identify behaviourally similar offences committed by the same unknown perpetrator (called linked offences). s considers progressively higher-level taxa, such that two sites show some similarity even without shared species. We apply this index by analysing 55 specific offence behaviours classified hierarchically. The behaviours are taken from 16 sexual offences by seven juveniles where each offender committed two or more offences. We demonstrate that both Jaccard and s show linked offences to be significantly more similar than unlinked offences. With up to 20% of the specific behaviours removed in simulations, s is equally or more effective at distinguishing linked offences than where Jaccard uses a full data set. Moreover, s retains significant difference between linked and unlinked pairs, with up to 50% of the specific behaviours removed. As police decision-making often depends upon incomplete data, s has clear advantages and its application may extend to other crime types. Copyright © 2007 John Wiley & Sons, Ltd.
Thesis (Ph. D.)--Simon Fraser University, 1995. Includes bibliographical references.
Intelligence analysis has emerged as an important component of contemporary policing strategies. Drawing upon qualitative data and a perspective informed by some of the concepts associated with the sociology of scientific knowledge, this paper provides an epistemologically oriented critique of some of the key techniques associated with crime analysis. Data presented suggest that crime analysis: is used in line with traditional modes of policing; is a way of claiming ‘scientific objectivity’ for police actions; and is largely shaped by police perspectives on data. It is argued that the sense of enhanced objectivity often attributed to the products of ‘intelligence work’ is frequently overstated. The products of crime analysis are better understood as an artefact of the data and methods used in their construction, rather than providing an accurate representation of any crime problems.