How to get away with (sexual) murder? Unraveling cold cases in sexual homicide using a hybrid modeling probabilistic approach.

This study examines Sexual Homicide (SH) cases, analyzing the transition to cold cases through a non-discretionary lens. Utilizing the SH International Database, it explores the interplay between offender behavior, victim characteristics, and crime context. Advanced methodologies, including sequential logistic regression and Artificial Neural Networks, identify key predictors of case resolution. Results highlight the critical influence of victim intoxication, high-risk activities, and the location of the victim's body on case solvability. The study also reveals the significant role of offender forensic awareness and the complexity of crime scenes in hindering case resolution. These findings underline the multifaceted nature of SH cases, emphasizing the importance of understanding the nuanced interplay between victim, offender, and contextual factors in solving these challenging cases.

Trophy, souvenir, or simple theft? Taking items from the victim in sexual homicide.

Although most people have heard the terms 'souvenirs', 'trophies', and 'mementos', discussed in books and movies on the true crimes of sexual murderers, limited research has delved into the phenomenon of theft in sexual homicide (SH). Using a sample of 762 SH cases coming from the Sexual Homicide International Database, the current study examines the crime-commission process of the pre-crime, crime, and post-crime phases of sexual homicide offenders (SHOs) who engaged in theft during a SH. Additionally, this study seeks to determine if a specific type of SHO engages in this behaviour over others. Results from the sequential logistic regression indicate that victims who are 16 years or older, were strangers to the SHO, and were sex workers were more likely to be victims of theft. Additionally, results indicate that the presence of sadism made it more likely the SHO would engage in theft from the victim and/or crime scene. Findings suggest there is a group of SHOs who engage in theft not for monetary purposes but due to the paraphilia of the offender. These findings can inform the police investigation of these crimes.

Energetics of twisted elastic filament pairs.

We investigate the elastic energy stored in a filament pair as a function of applied twist by measuring torque under prescribed end-to-end separation conditions. We show that the torque increases rapidly to a peak with applied twist when the filaments are initially separate, then decreases to a minimum as the filaments cross and come into contact. The torque then increases again while the filaments form a double helix with increasing twist. A nonlinear elasto-geometric model that combines the effect of geometrical nonlinearities with large stretching and self-twist is shown to capture the evolution of the helical geometry, torque profile, and stored energy with twist. We find that a large fraction of the total energy is stored in stretching the filaments, which increases with separation distance and applied tension. We find that only a small fraction of energy is stored in the form of bending energy, and that the contribution due to contact energy is negligible. Further, we provide analytical formulas for the torque observed as a function of the applied twist and the inverse relation of the observed angle for a given applied torque in the Hookean limit. Our study highlights the consequences of stretchablility on filament twisting, which is a fundamental topological transformation relevant to making ropes, tying shoelaces, actuating robots, and the physical properties of entangled polymers.

A Criminological Perspective on the Sexual Victimization of Older Adults.

PURPOSE OF REVIEW: This review presents recent research on the sexual abuse of older adults and examines this phenomenon from a criminological perspective. Much of the previous work has neglected to consider the entirety of the crime-commission process. Therefore, the work highlighted in this review showcases important information regarding the individual who committed the crime, the victim, and the criminal event as a whole. RECENT FINDINGS: Comparative studies suggest that the motivations of people who commit sexually victimize older adults are vast and can include those that are sexually and anger motivated, while the victims present with unique vulnerabilities, such as disabilities and spending most of their time at home, that make them more susceptible to excessive violence. People who commit sexual abuse against older adults are a heterogenous group, and the context of victim vulnerabilities is key to understanding why they are targeted. Specific prevention and investigative practices can be formed to better address this crime and protect older adults from future victimization.

Violent Partners or a Specific Class of Offenders? A Criminal Career Approach to Understanding Men Involved in Intimate Partner Sexual Violence.

The current study investigates the criminal career of individuals involved in intimate partner sexual violence (IPSV). Specifically, the goal is to determine whether men who engage in IPSV can be distinguished from those who engage in intimate partner non sexual violence (IPNSV) only and whether criminal trajectories in the resulting subgroup are heterogeneous. The sample comes from a Canadian database including a total of 12,458 individuals involved in IPSV and 32,474 individuals involved in IPNSV). Bivariate and multivariate analyses are performed to examine the differences in the two groups while latent profile analysis allows examining the heterogeneity of characteristics of men who engaged in IPSV. Findings indicate that the criminal career of men who engage in IPSV follows a pattern that is clearly distinct from that of men who engage in IPNSV only and is more specialized in terms of sexual offenses. Results also show that the criminal trajectories followed by the men who engage in IPSV are heterogeneous. Four profiles of different trajectories were identified. Both theoretical and practical implications are discussed.

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.

Adverse childhood experience trajectories and individual high risk-behaviors of sexual offenders: A developmental victimology perspective.

BACKGROUND: Developmental victimology theory suggests that developmental features of risk and impact stemming from various types of victimization depend on the age of the child or adolescent. OBJECTIVE: A next step is studying the developmental victimization trajectories of individuals involved in sexual crimes by focusing on traumatic events occurring during childhood and adolescence respectively. Building on the developmental victimology perspective, the study's specific aims encompass two key objectives: 1) exploring the diverse trajectories of Adverse Childhood Experiences (ACEs) within a sample of individuals involved in sexual crimes, and 2) assessing whether these ACEs trajectories influence the emergence of distinct high-risk behaviors. PARTICIPANTS AND SETTING: 252 individuals convicted of sexual crimes were selected from a federal penitentiary in Quebec, Canada. METHODS: Semi-structured interviews with a computerized questionnaire produced data on numerous aspects of the participant's life history, criminal career, and victimization experiences that were analyzed via latent class modeling. RESULTS: Four classes (no ACEs trajectory, poly exposure and victimization trajectory, childhood exposure trajectory, and poly victimization trajectory) were identified. CONCLUSIONS: Consistent with hypotheses, developmental ACEs trajectories are heterogeneous and associated with the criminal careers, adolescent problematic behaviors, substance use disorders, and violence history among individuals involved in sexual offending.

Strangulation in sexual homicide: Is it opportunity, victim's vulnerability or sadism?

Although most homicides involve the use of a weapon, some offenders still prefer killing with their own hands, using strangulation. In fact, when disaggregating the various types of homicides, sexual homicide offenders appear as having a preference for "personal weapon" to kill the victim. Personal weapons, such as strangulation, asphyxiation, and beating, are the most commonly used killing methods in sexual homicide. Using a sample of 451 cases of sexual homicide of adult female, the current study examines three hypotheses as to why strangulation is the method of choice to kill in sexual homicide: 1) weapon of opportunity, 2) victim's vulnerability, and 3) sexual sadism. Results from logistic regressions and artificial neural network analysis show that all three hypotheses are supported, sexual homicide offenders using strangulation being less likely to target a victim with a strong build, to bring and use a weapon. However, strangulation is more likely to be used to kill the victim when the offender is characterized with sadism. Implications of the findings are discussed in light of our understanding of the crime-commission process involved in sexual homicide.

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.

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.

Developmental Sequela for Sexual Homicide: Testing an Integrated Multi-Theoretical Model.

Research focusing on the role of adverse childhood experience (ACE) of individuals involved in sexual homicide (SH) is scarce. Theoretical models of SH have postulated a connection between these adverse experiences and the development of internal risk factors. However, such assumptions have never been empirically tested. Therefore, the current research aims to identify how ACEs affect the development of personality disorders and problematic behaviors during adolescence, which constitute internal risk factors for the commission of SH. The sample comes from a database including 613 individuals involved in sexual crimes in Canada among which 60 committed a SH. Bivariate and multiple regression analyses were conducted to identify personality disorders and problematic behaviors during adolescence associated with the presence of ACEs. Next, path analysis was used to identify the direct and indirect relationships between ACEs, internal risk factors, and the commission of SH. Results showed that individuals who experienced ACEs were more likely to develop internal risk factors involved in the commission of SH. Moreover, findings suggest that the impact of these adverse experiences will differ, depending on whether the child has been victim of violence or if he/she has witnessed it.

Sadistic Sexual Crimes Against Children: Comparing the Manifestation of Sexual Sadism and Crime-Commission Process.

Individuals who commit sexual offenses against children have been shown to be distinctive from adult offenders across both individual and crime characteristics. However, an examination of the literature shows that there are gaps in the research related to whether sadism manifests differently between those who target child compared to adult victims. The current study therefore aimed to explore the differences in the characteristics, crime-commission process, and the dimensions of sadism between sadistic crimes of children (n = 101) compared to those of adults (n = 433). Sexual sadism was assessed with the Sexual Sadism Scale (SeSaS) and binary logistic regression analysis and multidimensional scale analysis (MDS) were performed to examine differences between these two groups. Our results showed that sadistic fantasies manifested into four dimensions for both adult and child victims. In terms of differences, sadistic sexual offenses involving children appear to be reflective of deviant fantasies related to overlapping paraphilias (e.g., sadism and pedophilia). Conversely, sadistic crimes involving adult victims involve a crime-commission process that involves a greater degree of structure to control their adult victim and decrease their risk of identification. Implications for clinical assessment and police investigations are discussed.

Sexual homicide and the forensic process: The decision-making process of collecting and analyzing traces and its implication for crime solving.

The focus of the current study is to examine the collection and analysis of traces that are related to crime scene behaviors in sexual homicide cases as well as the factors influencing the solving of these crimes. Using 230 sexual homicide cases from the SHielD database, we computed two neural network models based on the multi-layer perceptron algorithm. First, we determined whether certain crime scene characteristics predicted the collection and analysis of traces (dependent variable for Model 1). Not surprisingly, the results indicate that trace collection and analysis were more likely to occur in sexual homicide cases with crime scene behaviors exhibiting the highest risk for trace transfer (e.g. close interactions with the victim) as well as the best conditions for trace persistence (e.g. body is found indoors). Situational and physical aspects of the crime scene are thus taken into account when deciding on the collection and analysis of traces. Second, we examined the situations in which the collection and analysis of traces contributes to crime solving (dependent variable for Model 2). The results suggest that the collection and analysis of traces does not necessarily predict the resolution of the case. Specifically, the analyses show that the collection and analysis of traces is useful for crime solving when: (1) the offenders' behaviors increase the opportunities for leaving traces at the crime scene, and (2) when the environmental and temporal aspects are favorable to the collection of traces. The impact of trace collection and analysis on case resolution is thus depending on the context of the case. Furthermore, the subsequent steps, such as the result of the trace analysis, the introduction into a database, the obtention of a result from this comparison, etc. might also affect case resolution, and thus interfere in the link between trace collection and analysis and case resolution.

Manifestations of sexual sadism in child sexual assault and the associated victim, offender, and offense characteristics: A latent class analysis.

BACKGROUND: Although sadistic child sexual abuse (SCSA) is rare, existing typologies of child sexual abuse have identified the existence of sadistic subtypes in child molestation, as well in the sexual homicide of children. Nonetheless, no study has sought to determine whether there is heterogeneity in the manifestation of sexual sadism between sadistic child abusers. OBJECTIVE: The present study seeks to examine how SCSA manifests differently between offenders, and whether these differences are associated with specific victim, offender, and offense characteristics. PARTICIPANTS AND SETTING: The current sample includes adult males (N = 101) who were involved in a child sexual assault and scored at least a 4 on the Severe Sexual Sadism Scale (SeSas). All offenses take place in France between 1990 and 2018. METHODS: Latent class analysis was used to analyze the sample for heterogeneity. Bivariate analyses were conducted to identify external variables associated with each of the latent classes. RESULTS: Three distinct latent classes were found: the sadistic kidnapper; the sadistic torturer; and the sadistic ritualist. External validity testing also revealed distinctive characteristics associated with each class. CONCLUSIONS: SCSA involves a heterogenous population with distinctive sadistic behavioral manifestations that vary in severity and relate to differences in crime-commission processes and offender characteristics. These findings offer important insights for crime prevention and correctional practice.

Childhood victimization and poly-victimization of online sexual offenders: A developmental psychopathology perspective.

BACKGROUND: Research on childhood victimization of individuals involved in online sexual offending during adulthood is scarce. Studies focusing on adverse childhood of individuals involved in offline child abuse suggested that childhood trauma was associated with an increased probability of sexual offending during adulthood. OBJECTIVE: The purpose of this study is to explore the role that childhood victimization may have in the development of risk factors that increase the likelihood of being involved in online sexual offending. PARTICIPANTS: This comparative study analyzed the characteristics of 127 individuals involved in online sexual offending who did not experience childhood victimization and 77 individuals involved in online sexual offending who experienced childhood victimization. METHODS: Bivariate and regression analyses were conducted to identify variables associated with the presence of victimization and polyvictimization during childhood. Next, structural equation modeling analysis was used to identify the direct and indirect relationships between childhood (poly)victimization and the development of risk factors. RESULTS: Results showed that individuals who experienced childhood victimization presented different risk factors and cognitions compared to those who did not. Depending on the type of victimization experienced, criminogenic cognitions, antisocial behaviors, and sexual interests for children were more likely to be developed. CONCLUSIONS: For individuals involved in online sexual offending during adulthood, childhood abuse is directly associated with the development of offense-supportive cognitions, substance abuse, and youth engagement in sexual offending, while sexual interests for children and sense of loneliness are indirect consequences of childhood trauma.

Tensional twist-folding of sheets into multilayered scrolled yarns.

Twisting sheets as a strategy to form functional yarns relies on millennia of human practice in making catguts and fabric wearables, but it still lacks overarching principles to guide their intricate architectures. We show that twisted hyperelastic sheets form multilayered self-scrolled yarns, through recursive folding and twist localization, that can be reconfigured and redeployed. We combine weakly nonlinear elasticity and origami to explain the observed ordered progression beyond the realm of perturbative models. Incorporating dominant stretching modes with folding kinematics, we explain the measured torque and energetics originating from geometric nonlinearities due to large displacements. Complementarily, we show that the resulting structures can be algorithmically generated using Schläfli symbols for star-shaped polygons. A geometric model is then introduced to explain the formation and structure of self-scrolled yarns. Our tensional twist-folding framework shows that origami can be harnessed to understand the transformation of stretchable sheets into self-assembled architectures with a simple twist.

Child sexual exploitation material offenders, one-size-fits-all for? Exploring tailored clinical dimensions based on cognitive and behavioural criminogenic factors.

BACKGROUND: Interventions for individuals involved in sexual offending behaviours are likely to be more effective if adapted to focus on their specific characteristics, suggesting that men who engage in sexual offences against children over the Internet should be treated differently from those who have actual physical contact against children. AIMS: The goal of this study is to explore possible associations between the criminogenic cognitions and behaviours of men using online child sexual exploitation material (CSEM) and variables relevant to intervention. We hypothesised that antisocial tendencies, sexual, emotional and relational problems and self-regulation problems, as well as cognitive distortions would be associated with CSEM use. METHOD: Ninety-eight men who had been convicted of at least one online CSEM-related offence, but no child contact sexual offences, at any time between 2001 and 2020 were recruited in the province of Quebec (Canada). Cases were reviewed to identify cognitive and behavioural criminogenic factors according to a coding sheet developed after reference to prior literature. Variables were extracted from official criminal records, sexological and psychological reports, as well as investigative and forensic reports and interviews. Exploratory factor analysis was carried out to identify potentially relevant dimensions. RESULTS: Analysis confirmed five distinct factors which, together, accounted for 60% of the variance: dissocial traits, dysfunctional intimacy, passive alienation (internalised sense of alienation), normless alienation (social norms experienced as alien) and coping with threat. CONCLUSION: Because online CSEM-related offenders present heterogeneous risks and needs, a 'one-size-fits-all' intervention is unlikely to be optimal for most of them. Our findings suggest a way of classifying risks and needs to facilitate more focused interventions. Future research should evaluate the relative effectiveness of general interventions compared to those tailored towards the dimensions of risks and needs identified in this study.

Sexual Sadism: Its Role in the Crime-Commission Process of Sexual Homicide of Children.

This study investigates the role of sexual sadism in the crime-commission process of sexual homicide (SH) involving child victims. A comparison between sadistic and nonsadistic cases involving child victims is conducted by examining the crime context, crime characteristics, methods of killing, body recovery characteristics, and forensic awareness strategies used by offenders. The sample comes from the Sexual Homicide International Database (SHIelD) including 135 cases of solved SHs involving child victims-35 cases with sexual sadism and 101 cases without sexual sadism. The Sexual Homicide Crime Scene Rating Scale for Sexual Sadism (SADSEX-SH) scale is used to identify sexual sadism from crime scene actions. Bivariate and multivariate analysis are performed to examine the differences between the two groups. Findings indicate that sadistic SH of children are characterized by an important level of structured premeditation, the commission of more diversified sexual acts, the use of specific method of killing, and the partial use of forensic awareness strategies. Practical implications in terms of criminal investigations are discussed.

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.

Foreign Object Insertion in Sexual Homicide: A New Perspective.

Foreign object insertion (FOI) is considered as an unusual behavior and has been defined as the involuntary insertion of any object, by another individual, into any orifice of the victim. Although there is some research on the prevalence and nature of FOI in sexual homicides, there is very little on the characteristics of cases where FOI occurs, and no previous research has compared cases with and without FOI. Given the lack of research on FOI in general and the dissemination of untested ideas regarding the correlates of this behavior specifically, the current study aims to shine new light on sexual homicide cases involving FOI by examining the offender, victim, and crime characteristics associated with FOI. Using a sample of 662 cases of sexual homicide, chi-square and logistic regression analyses were used to compare cases with and without FOI. Results showed that offenders who experienced sexual dysfunction and victims who used alcohol/drugs prior to the crime were more likely to be involved in cases with FOI. Cases where victims were beaten, vaginal/anal fisting acts were perpetrated, and mutilation of genitals were observed, were more likely to show evidence of FOI. Finally, postmortem sexual activities and the use of strategies by offenders to avoid police detection were also more likely to occur in sexual homicide cases characterized by FOI. These findings are discussed in light of the literature on sexual homicide, the vulnerability of victims, and the manifestation of sadism. Practical implications are also discussed.