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Sex Worker Homicide Series: Profiling The Crime Scene.
Abstract
Contrary to popular misconceptions, offenders who kill sex workers as part of their series exhibit substantial variability in their victim selection and behavioral patterns, thus creating additional issues for the investigation of these crimes. This article first aims to outline differences in the demographics of crime scene actions present in homicide series with exclusively sex worker victims and series that includes both sex worker and non–sex worker victims, with the aim of understanding the crime scene aetiology of these two different types of series. Second, the research aims to determine between-series differences of victimology as well as crime scene action between sex worker series and mixed-victim series. Third, the research focuses on mixed-victim series and aims to determine the within-series similarities of victimology and crime scene actions, that is, what factors link sex worker victims and non–sex worker victims in the same series. Data were collected through a large-scale review of international media sources to identify solved serial homicide cases that have included at least one sex worker. Of the 83 series looked at, 44 (53%) included sex worker victims only, and 39 (47%) of the series included both sex worker and non–sex worker victims. The findings highlight the challenges that these types of crime present for investigation and the implications they have on current crime analysis research and practice, and results are discussed in line with theoretical and psychological issues relating to understanding differentiation and similarity, as well as investigative implications relating to linkage blindness and linking of serial crimes.
... In the UK, Cunningham et al. (2018) also pointed out that some of the serial offenders in their sample were known only to have targeted sex workers and others had both sex worker and non-sex worker victims. Sorochinski and Salfati (2019) and Salfati and Sorochinski (2019) report in their studies that of their dataset of sex worker serial homicides, 53% were series that included only sex worker victims, and 47% of series included sex worker victims as well as other types of victims. Finally, Sorochinski and Salfati (2019) found that 17% of the victims in their dataset of homicide series that involved sex workers were sexually assaulted, and left alive. ...
... Sorochinski and Salfati (2019) and Salfati and Sorochinski (2019) report in their studies that of their dataset of sex worker serial homicides, 53% were series that included only sex worker victims, and 47% of series included sex worker victims as well as other types of victims. Finally, Sorochinski and Salfati (2019) found that 17% of the victims in their dataset of homicide series that involved sex workers were sexually assaulted, and left alive. Thus, not only do offender shows an inconsistency in the type of victim that they target but also an inconsistency in the overall type of crime (i.e., homicide vs. sexual assault) that they engage in. ...
... To enable cross-study comparison, a subset of the original analysis was used for the current study so that results may be able to be matched to previous studies done on this dataset Sorochinski and Salfati 2019). For this analysis, the first five crime scenes (or fewer if the series had fewer than five crimes) of the series were chosen. ...
Three general interlinked areas have been the focus of offender profiling research: individual differentiation (establishing differences between the behavioral actions of crime scene types), behavioral consistency (understanding behavioral patterns across a series of crimes), and offender profiling (linking sub-types of crime scene patterns to the most likely characteristics of an offender). Taken together, these three areas form the empirical basis necessary for use in criminal investigations. However, studies supporting inferences about offender characteristics have to date been the least developed in the field of offender profiling. For profiling to be fully useful to investigations, a clear understanding of three main elements is crucial to fully develop, notably (1) what individual crime scene characteristics are the most salient to use; (2) what elements of the full series behavioral developmental pattern are important to understand as an additional factor; and (3) what offender characteristics are the most empirically robust to focus on for investigative use. The current study examines 80 series of serial homicide, involving 302 crime scenes. Using the key elements of an offender’s crime scene behavioral patterns shown to help link and differentiate crime scenes and series, the current study linked these to sub-sets of different offender characteristics, identified as most useful for investigations. These included such characteristics such as age at the start of the series, criminal history specialization, general history of violence, mental health history, and relationship to the victims in the series. Results are discussed in the context of implications for research and practical applications in serial crime investigation and offender profiling.
... These studies go beyond simply demonstrating the statistical evidence for similarities between random pairs of crimes within series, to more specifically examine the patterns of development, consistency, and change across an offender's full series, so as to start understanding the possible psychology that may underlie an offender's behavioral patterns across time-a much more important and pertinent question when we aim to understand offending patterns in serial crimes, and how this may affect actually linking in investigative practice. From this small pool of studies that have looked at behavioral consistency and inconsistency, Salfati (2019) draws out some of the key results relating to both salient features to focus on, as well as patterns that have started to emerge (for a detailed review of these behavioral consistency studies, see Salfati, 2019). ...
... At the heart of the behavioral crime scene analysis work, therefore, has been the question of the role of the victim, as well as the key question of the consistency with which offenders are targeting certain subtypes of victims, and the prevalence of victim type switching from one crime to the next as the series continues. One of the groups of victims of particular focus in the work on serial sexual offenses has been that of vulnerable victims, and subgroups of highly targeted women in serial homicides, such as sex workers (see Sorochinski & Salfati, 2019, for a review). ...
... In this way, consistency is not contained within legal boundaries which do not necessarily follow patterns of human behavior, but instead taking a more global look at understanding the trajectory of the behaviors of the offender over time. Indeed, Sorochinski and Salfati (2019) found that 17% of the victims in their data set of homicide series were actually deliberately left alive by the offender while having been sexually assaulted. Thus, not only do offender show an inconsistency in the type of victim that they target but also an inconsistency in the overall type of crime (i.e., homicide vs. sexual assault) that they engage in. ...
Sex workers as a group are one of the more common targets in serial homicide, yet the most likely to go unsolved. Part of the reason for this is the difficulty in linking individual crime scenes to a series, especially in those series where offenders not only target sex worker victims but also target non-sex worker victims. Inconsistencies in both victim targeting and behaviors engaged in across series add to the difficulties of linking and solvability in these types of crimes. The current study aimed to add to the current body of literature on serial crime linkage by examining not only the most salient behavioral indicators useful for crime scene classification of serial homicides that involve sex worker victims but also examine the trajectories of behavioral change that can help link apparently inconsistent crime scenes and proposes the new Model for the Analysis of Trajectories and Consistency in Homicide (MATCH). The study examines 83 homicide series, including 44 (53%) series where all victims were sex workers and 39 (47%) series that included a mix of sex workers and non-sex worker victims. Using the MATCH system allowed for the majority of series to be classified to a dominant trajectory pattern, over half as many as a traditional consistency analysis that focusses on behavioral similarity matching. Results further showed that Sex Worker Victim series were almost three times more consistent across their series than Mixed-Victim series, not only in victim selection but also in the overall behavioral patterns. Findings are discussed in line with theoretical and psychological issues relating to understanding the nature of behavioral consistency and the importance of going beyond simple matching toward a model that allows for the identification of consistency in seemingly inconsistent series, as well as investigative implications relating to linking serial crimes.
... These studies go beyond simply demonstrating the statistical evidence for similarities between random pairs of crimes within series, to more specifically examine the patterns of development, consistency, and change across an offender's full series, so as to start understanding the possible psychology that may underlie an offender's behavioral patterns across time-a much more important and pertinent question when we aim to understand offending patterns in serial crimes, and how this may affect actually linking in investigative practice. From this small pool of studies that have looked at behavioral consistency and inconsistency, Salfati (2019) draws out some of the key results relating to both salient features to focus on, as well as patterns that have started to emerge (for a detailed review of these behavioral consistency studies, see Salfati, 2019). ...
... At the heart of the behavioral crime scene analysis work, therefore, has been the question of the role of the victim, as well as the key question of the consistency with which offenders are targeting certain subtypes of victims, and the prevalence of victim type switching from one crime to the next as the series continues. One of the groups of victims of particular focus in the work on serial sexual offenses has been that of vulnerable victims, and subgroups of highly targeted women in serial homicides, such as sex workers (see Sorochinski & Salfati, 2019, for a review). ...
... In this way, consistency is not contained within legal boundaries which do not necessarily follow patterns of human behavior, but instead taking a more global look at understanding the trajectory of the behaviors of the offender over time. Indeed, Sorochinski and Salfati (2019) found that 17% of the victims in their data set of homicide series were actually deliberately left alive by the offender while having been sexually assaulted. Thus, not only do offender show an inconsistency in the type of victim that they target but also an inconsistency in the overall type of crime (i.e., homicide vs. sexual assault) that they engage in. ...
For details of this work please see: https://www.researchgate.net/publication/331501443_MATCH_A_New_Approach_for_Differentiating_Linking_Series_of_Sex_Worker_Homicides_and_Sexual_Assaults
... However, mixed findings were found in the limited numbers of studies that have examined sex worker homicides. For instance, Salfati et al. (2008) reported a mean age of 37 years in their sample of 46 male sex worker murderers in the UK, and Sorochinski and Salfati (2019) found that all 83 offenders who committed sex worker homicides in sixdifferent countries (e.g., the US, Canada, the UK, Australia, Austria, and Hong Kong) were males with a mean age of 32 years. Clearly, more research on sex worker homicides is required before more conclusive information on the relevant offender characteristics can be generated. ...
... Salfati et al. (2008) found that nearly all of their sample of female victims were adults, with an average age of 24 years old (ranging from 17 to 46 years). In the study by Sorochinski and Salfati (2019), 95.2% of the sampled victims were females, with most of them being white (61%) and with an average age of 27.6 years. ...
Sex workers are commonly claimed to be at heightened risk of fatal victimization. Although prior research indicates that the dynamics of sex worker homicides resemble sexual homicides more than nonsexual homicides, little is known about how these types of homicides compare in terms of offending patterns. This study considers a sample of 2,851 single‐victim, single‐offender homicide cases extracted from a 37‐year (1976–2012) US Supplementary Homicide Reports database, and compares the offender, victim, and offender characteristics of 243 sex worker homicides (189 males and 54 females) with those of 2608 sexual homicides (2474 males and 134 females). The findings suggest that the offender, victim, and offense characteristics of general, male‐offender, and female‐offender sex worker homicides are essentially different from the characteristics of sexual homicides. Logistic regressions further indicate that most offender, victim, and offense characteristics on the occurrence of general and male‐offender sex worker homicides were significantly associated with the perpetration of general and male‐offender sex worker homicides, with reference to sexual homicides. These findings offer insights relevant to the prioritization of criminal investigative practices.
... Prostitutes work either with their own client base (e.g., call girls, escorts, and streetwalkers) or on behalf of other individuals or industries that procure clients for them within a lucrative business (e.g., sex clubs) (McGuire and Gruter, 2003). Violence against prostitutes reifies a justification for violence against women and conveys the idea that prostitutes are at their client's disposal (Salfati et al., 2008;Zara et al., 2021), making them more at risk of violence and femicide (Sorochinski and Salfati, 2019). ...
Violence against women is a growing health problem, especially when perpetrated in intimate relationships. Despite increasing attention, there is little comparative evidence on the different types of violence involved and there is a paucity of research on sexual femicides. This study examines cases of violence against women in northern Italy, focusing on sexual and non-sexual femicides and comparing them with rape that does not result in femicides. The sample included 500 women who were victims of sexual and non-sexual femicides, and of rape. Results show sexual femicides mostly involved unknown victims or women who were prostitutes. Sexual femicidal offenders used improper weapons to kill their victims, acted in secluded locations, and fled the crime scene; their crime was more likely the result of predatory intentions, with antisociality and sexual deviance being the most significant factors related to this type of femicide. The criminal and violent pattern that characterized sexual femicides in this study shared significant similarities with the pattern of violence involved in rape. Rape victims were in fact mostly unknown, or involved in a brief relationship with their killer. When the victim was known it was more likely that the abuse occurred at home and in front of the woman's children. Rapists were often under the effect of alcohol or drugs. Non-sexual femicides mainly involved known victims, and they were more often committed in the context of domestic disputes. It was not seldom that the long relationship between the victim and perpetrator was likely to be characterized by contentiousness, suggesting that the woman was often victim of an oppressive climate of emotional tension and domination. Morbid jealousy contributed to aggravating the tone of a controlling relationship. Non-sexual femicides bore more similarities to cases of rape within the pattern of intimate partner violence. Findings are discussed in terms of their implications for prevention and intervention. KEYWORDS violence against women, sexual femicide, non-sexual femicide, intimate partner violence, rape Frontiers in Psychology 01 frontiersin.org Zara et al.
... Despite the growing scientific interest in specifically studying violence against prostitutes (e.g., Canter et al., 2016;Farley, 2004aFarley, , 2004bLowman, 2000;Quinet, 2011;Sorochinski & Salfati, 2019), it still remains an underexplored topic and is often disregarded in national and global agendas for preventing violence (Deering et al., 2014). Violence against prostitutes offers an opportunity to explore violence against women by comparing different types of violence and the dynamics of killing, and different risk settings where violence can lead to murder. ...
Violence against women is a form of gender violence, and the lethal aspect of it, defined as femicide, is a global health and human rights problem.
This study looked at 330 cases of femicide that occurred in North West Italy, between 1970 and 2020, committed by 303 male perpetrators. The victims included women who were prostitutes and those who were not.
Findings show that only a small proportion of femicide occurs within an anonymous setting: Victims were mostly killed by a man they knew. The type and intensity of the relationship was likely to affect how the violence occurred. In those cases in which victims and perpetrators had an intimate relationship, the risk of overkill, that is, an excessive use of violence that goes further than what is necessary to cause death, was four times higher in comparison with the murder of unknown victims. As with non-prostitutes, the risk of overkill was almost fourfold for those prostitutes who knew their perpetrators. Furthermore, when comparing prostitutes with any unknown victims, the risk of being overkilled was almost five times higher for the former, suggesting that prostitutes are more at risk of being murdered with excessive violence. In addition, prostitutes were more likely to be victims of sexual murder, postmortem mutilation, and being killed by men who had previous criminal records.
Women who are victims of violence are not a homogeneous group, although some of the psychosocial correlates are the same and relevance should be given to the features behind the type, intensity, and nature of the relationship between prostitutes and non-prostitutes and their perpetrators. These variables are what make violence against women a preventable problem.
... Of the current trends in homicide studies, some works have focused on prediction, given the major practical implications that it has on police investigations (González-Álvarez et al., 2015;Abreu et al., 2018;Fox and Farrington, 2018). Specifically, there has been an interest in examining the utility of criminal profiling, as a criminal investigation technique directed at assisting in the prioritization and detention of offenders (Chan et al., 2019;Pecino-Latorre et al., 2019a;Sorochinski and Salfati, 2019;Ivaskevics and Almond, 2020). Therefore, numerous typologies have been created for homicides, always based on empirical evidence to ensure a more rigorous and systematic profile creation process (Horning et al., 2015;Fujita et al., 2016;Khoshnood and Väfors Fritz, 2017;. ...
The Action System model offers a scientific foundation to the differentiation and classification of crimes, based on behavioral indicators, allowing the establishment of relationships between the actions carried out by the offender on the crime scene and their characteristics. Although it was originally developed for application to fires, its utility has been tested in distinct criminal typologies, with few studies having considered homicides. The objective of this study was to examine the effectiveness and validity of the Action System model to differentiate thematically between the structure of the homicides and to create a typology of simple homicides in Spain, based on the relationships between the modus operandi, characteristics of the victims and characteristics of the offenders. The sample consisted of 448 homicides. Four homicide typologies were identified: Expressive, Adaptive, Integrative and Conservative, which represent 87.5% of the studied cases. Expressive homicides are impulsive, with offenders having criminal records and previously knowing their victims. Adaptive homicides are linked to robberies and sexual aggressions, in which the victim and offender are strangers. Integrative homicides take place in the family environment, specifically female offenders and femicides. Conservative homicides are very well planned, highlighting the presence of post mortem actions. The findings of this work suggest that the Action System model is a useful theoretical framework for the identification of variations in criminal behavior and understanding of the psychological processes underlying the homicides. These results have practical implications in the academic setting, since they offer a global perspective as to how simple homicides in Spain may be differentiated, also within the framework of criminal profiling, specifically, suspect prioritization.
Although relatively rare, sexual homicide has stimulated research efforts to better understand and intervene in the prevention of such crime. However, specific high-risk victims such as sex-trade workers have been understudied. To contribute to the limited scientific literature on this topic, the current study examines the characteristics of the sexual victimization of sex-trade workers using a sample of 402 lethal and non-lethal cases. Bivariate and multivariate analyses indicated that the lethal outcome associated with the sexual victimization of sex-trade workers may not be associated with sadism and paraphilic behaviors, but rather by excessive violence and victim's vulnerabilities. Conjunctive analysis further indicated that the combination of excessive violence, victim's intoxication, situational factors, and crime characteristics was associated with the lethal sexual victimization of sex-trade workers. Findings suggest strategies for the development of situational prevention and intervention strategies.
Prior research has associated Craigslist.com and Backpage.com as sources of victimization, which in part resulted in the closure of the erotic services of each respective website. However, research also claims the introduction of Craigslist was associated with a reduction in female homicide rates across 30 large cities. This research acts as a supplemental analysis to Cunningham et al. by analyzing if Backpage.com, considered to be Craigslist’s successor, has similar effects on female homicide rates. When including measures of interest in each respective website, we find that Backpage is associated with a decrease in homicide rates for women. The purpose of this study is to extend the study conducted by Cunningham et al. through supplemental analysis. To determine the effect of online clearinghouses on female homicide rates, interest measures in Backpage along with the female homicide rates from 120 single city metropolitan and micropolitan areas over 14 years (2004–2018) were analyzed using multiple regression analyses. The regression analyses show that there is a statistically significant relationship between interest in Backpage and homicide rates for women. We find that Backpage is associated with a decrease in homicide rates for women.
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.
This article presents an analysis of occupational homicides of sex workers in the United Kingdom, 1990-2016. Characteristics of 110 people murdered between 1990 and 2016 are explored including the location of their murder, ethnicity, migration status, and gender. Key changes over time are noted including an increase in the number of sex workers murdered indoors as well as an increase in murdered migrant sex workers. By developing the concept of “occupational homicide,” we argue that sex worker homicide should be viewed as an occupational issue and that the distinction between work-related homicide and nonwork-related homicide should be accounted for in future studies and is essential to inform prostitution policy.
Background
Information on psychopathological characteristics of sexual homicide offenders is scarce.AimsTo investigate criminal, paraphilic and personality trait differences between serial and single-victim sexual homicide offenders.Methods
All 73 single-victim and 13 serial sexual homicide offenders presenting within a cohort of 671 men sentenced for sexual crimes between 1994 and 2005 and serving their sentence in one high-security Canadian prison and who consented to interview were assessed and compared on their offending patterns, personality pathology and paraphilic behaviours.ResultsSerial sexual homicide offenders were more likely than the single offenders to report deviant sexual fantasies, having selected victims with distinctive characteristics, to have targeted strangers, structured premeditation and/or verbal humiliation of their victims during the offences. Personality pathology, defined by at least two Diagnostic and Statistical Manual of Mental Disorders IV criteria for personality disorder, was common in both groups, but the serial offenders were more likely to have narcissistic, schizoid and/or obsessive–compulsive traits; they were also more likely to engage in sexual masochism, partialism, homosexual paedophilia, exhibitionism and/or voyeurism.Implications for practiceSamples of serial sexual homicide offenders will, fortunately, always be small, and it may be that more could be learned to assist in preventing such crimes if data from several studies or centres were pooled. Our findings suggest that an investigation of sexual homicide offenders should include strategies for evaluating premeditation as well as personality and paraphilic characteristics. Crime scene features that should alert investigators should include similar characteristics between victims and particular aspects of body exposure or organisation. Copyright © 2014 John Wiley & Sons, Ltd.
This work includes a count of solved serial murder cases in the United States from 1970 to 2009. The number of serial murder cases has declined; the likelihood that a victim is a female has increased somewhat and although the numbers of all types of serial murder victims has declined, when a case occurs, victims are increasingly likely to be prostitutes, particularly female prostitutes. U.S. serial murder cases with prostitute victims accounted for 32% of all U.S. serial murder cases involving female victims only, 1970-2009. However, the proportion of solved cases involving female prostitute victims only increased across the study period from 16% during 1970-1979 to a high of 69% during 2000-2009. Prostitute killers amass a greater average number of victims than do nonprostitute killers and when analyzed by decade, those who kill primarily prostitutes, kill for slightly longer periods of time. The implications of findings for prevention and investigation efforts are discussed.
Sex workers as a group are one of the more common targets in serial homicide, yet the most likely to go unsolved. Part of the reason for this is the difficulty in linking individual crime scenes to a series, especially in those series where offenders not only target sex worker victims but also target non-sex worker victims. Inconsistencies in both victim targeting and behaviors engaged in across series add to the difficulties of linking and solvability in these types of crimes. The current study aimed to add to the current body of literature on serial crime linkage by examining not only the most salient behavioral indicators useful for crime scene classification of serial homicides that involve sex worker victims but also examine the trajectories of behavioral change that can help link apparently inconsistent crime scenes and proposes the new Model for the Analysis of Trajectories and Consistency in Homicide (MATCH). The study examines 83 homicide series, including 44 (53%) series where all victims were sex workers and 39 (47%) series that included a mix of sex workers and non-sex worker victims. Using the MATCH system allowed for the majority of series to be classified to a dominant trajectory pattern, over half as many as a traditional consistency analysis that focusses on behavioral similarity matching. Results further showed that Sex Worker Victim series were almost three times more consistent across their series than Mixed-Victim series, not only in victim selection but also in the overall behavioral patterns. Findings are discussed in line with theoretical and psychological issues relating to understanding the nature of behavioral consistency and the importance of going beyond simple matching toward a model that allows for the identification of consistency in seemingly inconsistent series, as well as investigative implications relating to linking serial crimes.
The methodology used to construct tree structured rules is the focus of this monograph. Unlike many other statistical procedures, which moved from pencil and paper to calculators, this text's use of trees was unthinkable before computers. Both the practical and theoretical sides have been developed in the authors' study of tree methods. Classification and Regression Trees reflects these two sides, covering the use of trees as a data analysis method, and in a more mathematical framework, proving some of their fundamental properties.
Chapter summary
• Sex worker victims are the single most targeted group in serial homicide offenses
• Only a subgroup of offenders consistently victimize sex workers, while others target both sex workers and other types of victims
• For offenders who target multiple types of victims, sex workers are only a part of their generalized pattern of violence and sex offending across their series
• Offenders who target multiple types of victims can further be differentiated based on the pattern of victim selection and type of activity with each type of victim, including sexual activity and level of violence
• Expanding our understanding of series composition and trajectories can increase linkage efforts by moving from focusing on only a single victim type (e.g., sex workers) or only a single crime type (e.g., sexual assault vs. sexual homicide) and by so doing, increase solvability
Book synopsis: As a society we are buying more sex than ever before. Adult sex shops now take their place amongst retailers in the high street and lap dancing clubs compete for an increased share of the leisure economy; hotel chains offer sexually explicit films as part of their standard service, the party selling of adult toys to women in their homes has become a mainstream activity; and at the traditional end of the sexual service economy, prostitution has experienced new growth. Along with this has come new legal measures and attempts to regulate the sexual leisure economy, and far more comprehensive plans than ever before to regulate prostitution, in particular in the form of the new Sex Offences Act. This book seeks to address the range of issues and contemporary debates on the sex industry, including the demand by customers who buy sex, the policing of women who work in the street sex industry, and the violence that pervades prostitution. It shows how these issues have been addressed in policy terms, the problems that have emerged in this, and how a social policy might be formulated to minimize harm and enhance public understanding. Overall the book aims to provide a critical perspective on prostitution policies and the legal chaos and complexities that surround this.
Key to understanding the significance of behavioural evidence for linkage purposes is in establishing how consistently an offender displays the same or similar behaviours across their series. There have however to date been very few studies aiming at identifying salient components of offending behaviour that can be used reliably for linking individual crimes as part of a single series. In addition, studies that have been conducted have all dealt with serial homicide in the Western world and have been based on small samples of cases from each country. Some of the recent literature has started to disentangle some of these salient features, notably the victim, violence levels, control, and planning. The current study focused on evaluating the consistency of these features across series, using a sample of serial homicides from South Africa consisting of 30 offenders with a total of 283 victims and 235 crime scenes. Results indicate that the level of interaction with the victim may be influential to the stability or instability of offending patterns across the series. How offenders approach planning in their offence also showed a certain degree of consistency, with patterns of violence being the least consistent across the series of all components tested. Copyright © 2014 John Wiley & Sons, Ltd.
Purpose
The study examines whether the use of forensic awareness strategies increases the chance of avoiding police detection in sexual homicide.
Methods
Logistic and negative binomial regression analyses are used on a sample of 350 cases of sexual homicide – 250 solved and 100 unsolved cases – in order to determine if forensic awareness strategies are related to the status of the case (i.e., solved versus unsolved) and the number of days before body recovery, while controlling for certain victim characteristics.
Results
Although an offender’s use of precautions does not seem to increase the offender’s chance of avoiding police detection, some modus operandi behavior adopted by the offender at the crime scene may help to delay the discovery of the victim, and thus delay the offender’s apprehension. Moreover, the likelihood of whether or not a sexual murderer is apprehended varied significantly across victim characteristics.
Conclusion
Some offenders seem to exhibit rational thinking in targeting certain types of victims and in adopting certain strategies in order to delay body recovery. Number of days until body recovery is a more appropriate measure of detection avoidance than case status, as it is not biased by administrative rules or timing of data entry.
The purpose of this paper is to identify and clarify the issues facing our society resulting from the phenomenon of serial murder. It will be argued that the extent and prevalence of serial murders in our society today is an indirect effect of the almost total lack of sharing or coordination of investigative information relating to unsolved murders and to the lack of adequate networking among law enforcement agencies in this country. This lack of coordination and networking will be referred to as linkage blindness. This inability of law enforcement to link unsolved murders to a serial pattern greatly increases the probability that this serial sequence of murders will continue until the murderer makes a mistake.
Most studies of sexual murderers consist of small samples made up of primarily adult offenders. Accordingly, little is known about similarities and differences between juvenile (under 18) and adult (over 18) sexual murderers. This article is the first to utilise a large sample (n = 3845) that spans almost three decades (1976–2004) of Supplemental Homicide Reports data to analyse juvenile (n = 452) and adult (n = 3393) sexual murderers, particularly in terms of weapons used to kill different victim types. This study underscores the importance of analyses of specific types of murderers. In comparison with homicide arrestees, those arrested for sexual murder were more likely to be male, less likely to be black, and about as likely to be under 18. Consistent with previous literature, sexual murderers in this study were more likely to use personal and close contact weapons than firearms and other more distant methods of killing. Several significant differences emerged in weapons selected to kill different victim types between juvenile and adult offenders. Findings with respect to weapon selection by offender age groups are consistent with Heide's physical strength hypothesis. Copyright © 2009 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. 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.
Offender profiling postulates that crime scene behavior should predict certain offender characteristics. The aim of this study
is to investigate the relationship between offender characteristics, situational factors, and body disposal patterns. Sequential
logistic regression analysis on a sample of 85 sexual murderers shows that those who were in a relationship at the time of
the crime and who present organized psychological characteristics are more likely to move the victim’s body after the homicide.
However, when the victim is older and a conflict with the offender occurred prior to the crime, the body is more likely to
be left at the crime scene. Implications for offender profiling are discussed in light of the results.
The aim of this study was to investigate specific pathways in the offending processes of nonserial sexual murderers and to examine possible relationships with different precrime, per-crime, and postcrime factors. Included in this study were 36 offenders who have committed at least one sexual murder against a female victim and they were classified using cluster analysis. Participants using the sadistic pathway planned their offenses and used physical restraints during the offenses. Furthermore, they mutilated and humiliated their victims. Finally, they hid the bodies of the victims. Participants using the anger pathway had not premeditated the homicide. Mutilation, humiliation, and physical restraints were less predominant with these participants than with those using the sadistic pathway. Moreover, these offenders were more likely to leave the bodies at the crime scenes after the killings occurred. These two profiles are compared with empirical studies addressing sexual homicide.
Prostitute women have the highest homicide victimization rate of any set of women ever studied. We analyzed nine diverse homicide data sets to examine the extent, trends, and perpetrators of prostitution-related homicide in the United States. Most data sources substantially under-ascertained prostitute homicides. As estimated from a conservative capture-recapture analysis, 2.7% of female homicide victims in the United States between 1982 and 2000 were prostitutes. Frequencies of recorded prostitute and client homicides increased substantially in the late 1980s and early 1990s; nearly all of the few observed pimp homicides occurred before the late 1980s. These trends may be linked to the rise of crack cocaine use. Prostitutes were killed primarily by clients, clients were killed mainly by prostitutes, and pimps were killed predominantly by pimps. Another conservative estimate suggests that serial killers accounted for 35% of prostitute homicides. Proactive surveillance of, and evidence collection from, clients and prostitutes might enhance the investigation of prostitution-related homicide.
Establishing behavioral consistency in serial homicide offending behavior is essential when linking homicides together and to a common offender. An examination of 35 serial homicide behaviors utilized by 90 offenders in 450 serial homicide cases was carried out to identify whether these offenders consistently performed the same behaviors across their series of homicides and whether it is more effective to examine individual behaviors or groupings of behaviors in order to identify behavioral consistency. This study provides the first empirically based evidence testing the use of using single behaviors as linking factors in linking homicide cases in a series, and shows that this method has inherent difficulties in accomplishing this, thus providing the first wave of empirical testing that questions current theories in the literature on serial homicide, which has suggested that signatures or specific key behaviors are important in understanding the consistency in an offender's behavior across the crimes. Recommendations for future studies on linking using signatures are suggested, including a more in-depth qualitative empirical evaluation of individual series.
It has been estimated that women involved in street prostitution are 60 to 100 times more likely to be murdered than are nonprostitute females. In addition, homicides of prostitutes are notoriously difficult to investigate and, as such, many cases remain unsolved. Despite this large risk factor, little literature exists on homicides of prostitutes, and there is a lack of basic statistics and knowledge regarding this very specific victim group that could possibly help investigators. The aim of the current study is to conduct an exploratory study to explore the key characteristics of this group and how they differ from other subgroups of homicide. Forty-six cases of U.K. prostitute homicides are analyzed and compared to 59 male offender-female victim nonsexual homicide cases and 17 male offender-female victim sexual homicide cases.
Homicides Involving Prostitutes (HIP©) coding dictionary
- C G Salfati
- M Sorochinski
Salfati, C. G., & Sorochinski, M. (2016). Homicides Involving Prostitutes (HIP©) coding dictionary. In Investigative Psychology Research Unit (IPRU). Retrieved from https://www.
jjay.cuny.edu/ipru/research
Patterns of sex worker and non-sex worker victim selection: Relationship to offender characteristics. Poster presented at The American Society of Criminology
- M M Abrams
- B Palmer
- C G Salfati
Abrams, M. M., Palmer, B., & Salfati, C. G. (2016, November). Patterns of sex worker and
non-sex worker victim selection: Relationship to offender characteristics. Poster presented
at The American Society of Criminology, New Orleans, LA.
Prostitutes: Vulnerable or sexual targets of serial homicide? Presented at the Annual American Society of Criminology Conference
- C G Salfati
Salfati, C. G. (2007, November). Prostitutes: Vulnerable or sexual targets of serial homicide?
Presented at the Annual American Society of Criminology Conference, Atlanta, GA.
Sexual murderers: Theories, assessment and treatment. In Sexual homicide and paraphilias: The correctional service of Canada's experts forum
- J Proulx
Proulx, J. (2007). Sexual murderers: Theories, assessment and treatment. In Sexual homicide and paraphilias: The correctional service of Canada's experts forum (pp. 215-233).