Rapists' behaviour: a three aspect model as a basis for analysis and the identification of serial crime

Interactions Between Offender and Crime Characteristics Leading to a Lethal Outcome in Cases of Sexually-Motivated Abductions

Despite the widespread public concern regarding abduction, research on this type of crime is scarce. This lack of research is even more pronounced when looking at cases that end with the death of the victim. In fact, all of the research looking at lethal outcomes in cases of abductions has focused exclusively on child victims and has failed to consider the interactions at the multivariate level between the factors related to the death of the victim. Therefore, the aim of the study is to identify offender and crime characteristics - as well as their interactions - associated with a lethal outcome in sexually-motivated abductions using a combination of logistic regression and neural network analyses on a sample of 281 cases (81 cases ending with a lethal outcome, random sample of 200 comparison cases). Findings show that sexually-motivated abductions ending with a lethal outcome are more likely to be characterized by an offender who is a loner, forensically aware, and who who uses a weapon and restraints, and who sexually penetrates and beats a known victim. The neural network analysis show that three different pathways lead to a lethal outcome in sexually-motivated abductions. Such findings are important for correctional practices.

The Unusual Case of Sexual Homicide Against Males: Comparisons and Classification

This study examines the specificities of sexual homicides involving male victims. First, this study aims to identify characteristics specific to SH involving male victims by comparing them to SH involving female victims and determine whether rational choice approach and routine activities theories are useful to explain the crime-commission process. Second, this study aims to provide the first empirical classification of SH involving male victims. The sample used in this research comes from the Sexual Homicide International Database (SHIelD) including 662 cases of cases-100 cases involving male victims and 552 involving female victims. Bivariate and multivariate analysis are performed to examine the differences between the two groups and latent class analysis is used to generate an empirical classification of cases involving male victims. Findings indicate the victim's gender plays an important role in the different choices made by sexual homicide offenders of male victims to successfully complete their crime. They adapted their crime-commission process to overcome the risks associated with a physical confrontation with a male victim (i.e., target selection, approach strategy, method of killing). Classification analysis suggests that it exists three different types of sexual murderers assaulting male victims: the robber sexual murderer, the sadistic sexual murderer, and the pedophile murderer. This research proposes the first empirical typology of sexual homicide involving male victims and provides both a true picture of the reality and a comprehensive understanding of this phenomenon.

Modus Operandi in Sexual Assaults of Female Strangers Does Not Change Over Time

Criminological theories and widespread assumptions about crime suggest that the modus operandi involved in sexual crimes should have changed over time given various contextual changes, such as better criminological knowledge (e.g., forensic awareness) as well as improved investigative techniques (e.g., forensic evidence analysis). The aim of this study was to test whether the modus operandi patterns of individuals having committed a sexual assault against female strangers have changed over time during the period of 2003-2017. More specifically, the study has identified changes in the trends of monthly counts and (relative) participations for sexual assaults during the study period in France. The measure of participations - a concept borrowed from the field of criminal career - was used to overcome the inherent limitations associated with this type of data. Results show that despite some significant changes in the modus operandi involved in sexual crimes, overall the modus operandi patterns appear to be fairly stable over time. The findings are discussed in light of their theoretical and practical implications.

Onset Crime Typology of Sexual Offenders and Their Differences on Specialization and Risk Factors

In those theories or empirical-evident model of sexual offending, they all recognized which major life event would cause the sex offense in some conditions, therefore the onset crime of sexual offenders were not only a mark of personal history, but also could reflect the heterogeneity of sexual offenders. Our purpose is to study the onset crime typology of sexual offender and their difference in specialization, problem of psychology marks, and negative developmental experiences. We analyzed the pre-conviction data from 3,750 sexual offenders and their risk assessment data. The research results found that onset typology of sex crime would persist their criminal career into sexual offending, and through the group comparisons, the study pointed out differences in risk factors domain and adverse development experiences. We also discussed those research results and their meaning of risk management.

One and a half centuries of serial homicide in Italy: offender, victim and offence characteristics

The present study reports offender, victim and offence characteristics of the entire population of known serial homicide offenders identified in Italy between 1848 and 2019 (59 offenders, 244 victims, of whom 50.4% were men, and 21.7% were sex workers). We found that most of the offenders (72.4%) had a personality disorder. The offenders' age during their series was 35.1 (SD = 11.3) years, on average. Sexual elements were found in 28.4% of the crime scenes. The median time interval between homicides was 2.8 months. Also, we investigated the consistency of the offence characteristics over the series and found significant correlations between the offence characteristics between a previous and the subsequent homicide.

Expert Versus Novice: Criminal Expertise in Sexual Burglary and Sexual Robbery

Although there has been considerable variation in the application of expertise to offending populations, one aspect that is widely agreed upon is that expertise is best represented on a continuum from novice to expert. The present study, therefore, investigated criminal expertise in 877 hybrid offenses that involve sexual assault and robbery (i.e., sexual robbery) or burglary (i.e., sexual burglary). Specifically, we analyzed the crime-commission processes of both these offenses using latent class analyses to determine the heterogeneity of criminal expertise among each domain. Results showed an expert to novice continuum in both domains, including a "domain-specific" expert sexual burglary subgroup who was characterized by a high degree of offense-related competencies relevant to sexual burglary. We also found an expert subgroup in sexual robbery who had more general skills (i.e., overlapping expertise) relevant to violent offending. Implications for offender decision-making, treatment, and practice are discussed.

Is There an "Expert" Stranger Rapist?

The concept of expertise applied to the criminal context assumes that offenders are driven by the abilities to both maximize the payoffs and minimize the risks associated with the crime-commission. This study tested the articulation between these two types of decisions taken by stranger rapists to successfully commit their crime. Specifically, this study aims to identify whether offenders whose modus operandi is indicative of criminal expertise are more likely to use forensic awareness strategies. Multivariate analyses conducted on 1,551 cases showed that stranger rapists who adopted behaviors indicative of expertise were more likely to use forensic awareness strategies to decrease the risk of police detection. Mixed associations were found between the number of forensic awareness strategies and their nature (i.e., protecting identity vs. destroying evidence) and rapists' expertise, thus leading to a four-type theoretical classification of expertise: novice, bold, opportunistic, and expert stranger rapists. Implications for research and practice are discussed.

"Drop the Body": Body Disposal Patterns in Sexual Homicide

The current study investigates body disposal patterns in sexual homicide and examines whether offender's behavior differ between solved and unsolved cases. To address these two research questions in line with rational choice perspective, a series of logistic regression analyses was conducted on a sample of 250 solved, and 100 unsolved sexual homicide cases in Canada. Within solved cases, results show that if victim is a prostitute, body found concealed, and found lying face down, it is likely the body was moved. For unsolved cases, the role of victim as a prostitute, and body recovered outdoors suggest that the body was moved. Further, results indicate that post-crime phase factors predicted the most whether the victim's body was moved in solved cases. Whereas within unsolved cases, crime-phase factors contributed the most at predicting whether the body was moved post-homicide. Theoretical and practical implications from this study are discussed.

Sexual homicide in Australia and New Zealand: a description of offenders, offences and victims

The field of sexual homicide research is relatively recent, with many existing studies limited by small sample sizes and sampling bias. In Australia and New Zealand specifically, only one study to date addresses this phenomenon but there is a lack of comprehensive descriptive data. This study aims to fill this research gap using a representative sample gathered from public legal databases. A total of 118 cases of sexual homicide offenders are described to create a portrait of this type of offender, their victims and their offence behaviour. Findings are similar to those found in other large samples from the UK, Canada and Germany. Because this crime is rare and practitioners tend to have limited experience of them, the findings of this research have the potential to inform investigative, criminal justice and clinical practice.

Making sense of senseless murders: The who, what, when, and where?

The phenomenon of "senseless" or "motiveless" homicide refers to homicides that lack an objective external motivation. Despite the unique challenges these homicides pose to police, few empirical studies have been conducted on the topic and existing studies are limited to clinical studies using small samples. To overcome existing empirical shortcomings, the current study used a sample of 319 homicide cases where no motive was established during the investigation to describe the "who" (offender and victim characteristics), "what" (modus operandi, crime characteristics), "where" (encounter, crime, and body recovery associated locations), and "when" (time of the crime) of the entire criminal event. Findings provide insight into the entire crime-commission process and suggest a different dynamic to "senseless" homicide from what has been described in previous literature. Implications for police investigative practice are discussed.

An Analysis of Crime Scene Behavior in Korean Homicide

The aim of the current study is to identify themes of crime scene behaviors in a sample of 487 Korean homicides and test whether these themes are linked to offender characteristics. A content analysis of police information was first conducted and then a multidimensional scale approach was used to identify themes in the homicide data. The exploratory thematic structure showed four factors that confirmed the instrumental/expressive themes as being useful in differentiating homicides: sex-arousal, cognitive, overkill-blood, and impulsive. These four themes were compared with the previous themes identified in Western studies of homicide. Finally, the current findings support the idea that there are relationships between crime scene behavior themes in homicide and offender characteristics.

Internet Facilitated Rape: A Multivariate Model of Offense Behavior

Recent statistics report a significant increase in individuals reporting they have been raped by a stranger whom they have met through the Internet (Internet facilitated rape [IFR]). Previous literature has primarily focused on child victims; hence, the overriding aim of this study is to further our understanding of IFR in terms of crime scene behavior. One hundred forty-four IFR cases and two comparative samples of age-matched stranger rapists (confidence approach and surprise approach) were coded for 38 crime scene behaviors. Findings suggest that the platforms IFR offenders use to meet their victims were not suggestive of the behavior they were likely to display. In terms of specific offense behaviors, the IFR and confidence approach rapists were considerably similar and both samples were comparatively different from the surprise approach rapists. Thus, this may indicate that the method of approach used by a stranger rapist has a significant effect on the subsequent rape crime scene behavior displayed regardless of any prior contact. A smallest space analysis of the IFR sample revealed three distinct themes of behavior, criminal sophistication, interpersonal involvement, and violence with 71% of offenders displaying one dominant theme. The practical and theoretical implications of the findings are discussed.

Exploration of Crime-Scene Characteristics in Juvenile Homicide in the French-Speaking Part of Belgium

This study explores modeling crime-scene characteristics of juvenile homicide in the French-speaking part of Belgium. Multidimensional scaling analysis was carried out on crime-scene characteristics derived from the court files of 67 individuals under 22 years old, who had been charged with murder or attempted murder (1995-2009). Three thematic regions (Expressive: multiple offenders; Instrumental: theft; Instrumental: sex/forensic awareness) distinguished types of aggression displayed during the offense. These themes reaffirm that the expressive-instrumental differentiation found in general homicide studies is valuable when attempting to discriminate juvenile homicides. The proposed framework was found useful to classify the offenses, as 84% of homicides were assigned to a dominant theme. Additionally, associations between crime-scene characteristics and offenders' characteristics were analyzed, but no associations were found, therefore failing to provide empirical support for the homology assumption. Cultural comparisons, as well as the influence of age on the thematic structure are discussed.

Is Investigative Awareness a Distinctive Feature of Sexual Sadism?

Sadistic offenders are often described as individuals who are forensically aware, who carefully plan their offenses, and preselect the location of their crime. Despite this emphasis on strategies to avoid police detection, no study has specifically examined whether this behavior or trait was specific to sadistic offenders. Utilizing a sample of 350 cases of sexual homicide from Canada, sadistic sexual homicide offenders (SHOs) are compared with nonsadistic SHOs on their investigative awareness. Results from logistic regression analyses show that sadistic SHOs are more likely to use various precautions to avoid detection and select a deserted location, in comparison with nonsadistic offenders. In addition, sadistic SHOs, despite having a lesser time to body recovery than nonsadistic offenders, are more likely to see their case remain unsolved. Implications for the assessment of sexual sadism as well as for the police investigations will be discussed.

An Empirical Examination of the Victim-Search Methods Utilized by Serial Stranger Sexual Offenders: A Classification Approach

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.

Whiter Than White: The Art of Delaying Detection in Sexual Killers

The study investigated whether different types of sexual homicide perpetrators are more or less skilled at delaying detection. A newly proposed direct/indirect typology was used alongside information about the time of arrest, the frequency of specific precautions as well as the impact of forensic strategies used by the perpetrators to examine skill at delaying detection. The results indicated that the time from the killing to the arrest, as measured in days, was longer for the direct than the indirect sexual killers. Despite the fact that the direct aggressors were better at delaying detection, overall the indirect and the direct offenders did not differ in the frequency of use of most of the precautions. However, different forensic awareness strategies were more efficacious for the direct and the indirect offenders. These results are discussed in relation to the crime scripts for the two perpetrator groups.

A Cross-Cultural Comparison of Canadian and Korean Sexual Homicide

Sexual homicide is a crime of rare occurrence. However, crime severity surveys ranked this form of sexual violence as the second most serious crime. Despite an increase in recent years in the publication of empirical studies on sexual homicide, most of these studies originate from Western countries. Therefore, to our knowledge, no studies to date have tested whether the country where sexual homicides are committed influences the way these crimes are executed by the offenders. The current study attempts to shed additional light on the sexual homicide offender (SHO) by comparing Korean and Canadian SHOs as well as comparing both groups of SHOs with a group of nonsexual homicide offenders (NSHOs). Findings suggest that both Korean and Canadian sexual homicide cases present not only similar patterns but also some specific differences, mainly related to their criminal history, the offender's age, forensic awareness, and some modus operandi characteristics such as the type of violence and the use of a weapon. Findings are discussed in light of cultural differences between the two countries.

Murder by Pushing: An Exploratory Analysis of Homicidal Falls From a Height

The difficulty in classifying manner of death in falls from a height provides offenders an opportunity to avoid detection by having a homicide appear otherwise. Twelve fall homicides were qualitatively examined. Results showed that most homicidal falls occurred at remote outdoor locations, were planned by offenders who were in controlling intimate relationships with the victim, and were motivated by gain. Homicide was established using inconsistencies in offender's statements and the physical evidence, inappropriate postoffense behavior, evidence of planning, and improbable alleged victim behavior. Fall homicides pose unique challenges for investigators and may negatively impact on the criminal justice process.

Offender Mobility During the Crime: Investigating the Variability of Crime Event Contexts and Associated Outcomes in Stranger Sexual Assaults

Using data from qualitative interviews and police reports, latent class analysis is used on a sample of 54 repeat stranger sexual offenders who committed 204 sexual assaults to identify discrete contexts present at the time of victim encounter that influence these offenders' decision to use more than one location to commit their crimes. Five distinct classes are identified: residential outdoor common area, spontaneous/quiet outdoor site, residential home, active green space, and indoor/public gathering place. An investigation into the outcome(s) that most often result from the offender's decision to move the victim during the sexual assault indicates that those who move the victim from an active green space overwhelmingly engage in sexual penetration, as well as forcing their victims to commit sexual acts on them. Crimes where the victim is moved from a residential home show evidence of the offender physically harming the victim as well as using more force than necessary to complete the assault. Implications for situational crime prevention are discussed.

Does the Organized Sexual Murderer Better Delay and Avoid Detection?

According to the organized-disorganized model, organized sexual murderers adopt specific behaviors during the commission of their crimes that contribute to avoiding police detection. The current study examines the effect of sexual murderers' organized behaviors on their ability to both delay and/or avoid police detection. Using a combination of negative binomial and logistic regression analyses on a sample of 350 sexual murder cases, findings showed that although both measures of delaying and avoiding detection are positively correlated, different behavioral patterns were observed. For instance, offenders who moved the victim's body were more likely to avoid detection but the victim's body was likely to be recovered faster. Moreover, victim characteristics have an impact on both measures; however, this effect disappears for the measure of delaying detection once the organized behaviors are introduced. Implications of the findings are discussed.

A descriptive study of sexual homicide in Canada: implications for police investigation

Few empirical studies have been conducted that examine the phenomenon of sexual homicide, and among these studies, many have been limited by small sample size. Although interesting and informative, these studies may not be representative of the greater phenomenon of sexual murder and may be subject to sampling bias that could have significant effects on results. The current study aims to provide a descriptive analysis of the largest sample of sexual homicide cases across Canada in the past 62 years. In doing so, the study aims to examine offender and victim characteristics, victim targeting and access, and modus operandi. Findings show that cases of sexual homicide and sexual murderers included in the current study differ in many aspects from the portrait of the sexual murderer and his or her crime depicted in previous studies. The authors' results may prove useful to the police officers responsible for the investigation of these crimes.

South African serial rapists: the offenders, their victims, and their offenses

Serial rapists have the propensity to cause harm to a significant number of victims, meaning that they are of concern to the police as well as to treatment providers. Despite the serious nature of their offending, there are surprisingly few studies that provide information regarding their characteristics, the types of victim they target, or the nature of the sexual offenses they commit, and those studies that do exist are varied in their findings. This study provides a descriptive analysis of serial rape in South Africa. One hundred and nineteen sexual offenses committed by 22 serial rapists were sampled. Information regarding the victims, the offenders, and the crimes they had committed were extracted from police files. The characteristics of victims and offenders are reported as well as the frequencies for 114 different crime scene behaviors. When compared with samples of serial sex offenders from other countries, differences emerged in victim characteristics and crime scene behaviors, including how the victims were targeted, the sexual behaviors engaged in, and the incidence of physical violence. The implications of these observed differences for practice are discussed.

The significance of offending behavior for predicting sexual recidivism among sex offenders of various age groups

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.

Serial and single-victim rapists: differences in crime-scene violence, interpersonal involvement, and criminal sophistication

Three categories of crime-scene behaviors (violence, interpersonal involvement, and criminal sophistication) among a group of 22 serial and 22 single-victim rapists were studied. Findings indicate that serial rapists were more likely to display a higher level of criminally sophisticated behaviors to avoid detection, whereas single-victim rapists were more likely to behave violently and engage in some form of interpersonal involvement with their victims. Implications of these findings for investigation and for understanding offenders' behavior are discussed.

Linking commercial burglaries by modus operandi: tests using regression and ROC analysis

This paper uses statistical models to test directly the police practice of utilising modus operandi to link crimes to a common offender. Data from 86 solved commercial burglaries committed by 43 offenders are analysed using logistic regression analysis to identify behavioural features that reliably distinguish between linked and unlinked crime pairs. Receiver operating characteristic analysis is then used to assign each behavioural feature an overall level of predictive accuracy. The results indicate that certain features, in particular the distances between burglary locations, lead to high levels of predictive accuracy. This study therefore reveals some of the important consistencies in commercial burglary behaviour. These have theoretical value in helping to explain criminal activity. They also have practical value by providing the basis for a diagnostic tool that could be used in comparative case analysis.

Crime scene analysis and the escalation of violence in serial rape

The current study examines the crime scene behavior manifest by 108 serial rapists responsible for the perpetration of 565 rapes across various cities within the US. The goal of the current study is to identify which aspects of crime scene behavior reported to law enforcement by the victim are most useful in predicting, early in a series of offenses, which rapists are most likely to escalate into higher and, at times, life threatening levels of violence. Using 58 scales that quantify the verbal, physical, and sexual behavior manifest by a rapist in his interaction with his victim during his first reported rape and 36 modal variables that summarized approach, timing, demographics, and weapon usage across the series of rapes, the study attempts to differentiate between those rapists who escalate in their use of blunt force (Increasers) from those who do not (Non-Increasers). A logistic regression indicates that rapists who are white rather than of minority status and who, at the time of their first reported rape, rape their victims for longer periods of time and use more profanity are more likely to escalate in their level of blunt force than those rapists who do not exhibit these behaviors. The relevance of this type of predictive framework for law enforcement in its attempts to prioritize particular investigations is discussed.

Predicting the criminal antecedents of a stranger rapist from his offence behaviour

Approximately 85% of stranger rapists have criminal records, which usually contain a mixture of crime types. This study was designed to ascertain if inferences about such records could be made from aspects of offence behaviour, as described by the rape victims, focusing on both non-sexual behaviours and traits more obviously associated with previous criminality. The statistical technique used was logistic regression. The results demonstrated that it was very possible to obtain indications of a rapist's criminal antecedents from his offence behaviour. The three most promising models were those that predicted whether or not the offender had convictions for burglary, whether or not he had convictions for violent offences, and whether the offence was an apparent 'one-off' occurrence rather than the work of an experienced rapist.