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.

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.

Identifying victim types in sexual homicide: A latent class analysis using interactional victimology theories.

Sexual homicide (SH) research has focused on those who commit these crimes and the crimes themselves. This leaves the victim, an equally crucial piece to the puzzle, left as a sort of afterthought, despite the valuable insight that victimology provides to the crime. For the current study, victim information related to their routine activities and lifestyles was taken from an international database containing 662 solved cases of SH. Nine victim variables were used in a latent class analysis to find hidden subgroups within the victim population. Three classes were identified-low-risk, homebody, and overt risk victims-which suggests that SH victimization varies depending on the victim lifestyles and routine activities. These groups were externally validated by examining their association with different phases of the crime commission process. Some sexual homicide offenders may be more drawn to a victim because they present as vulnerable and opportunistic, while others might be methodically targeted. The theoretical relevance of this typology, along with investigative and prevention strategies, is discussed.

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.

Understanding sexual homicide in Korea using machine learning algorithms.

The current study was conducted to confirm the characteristics in sexual homicide and to explore variables that effectively differentiate sexual homicide and nonsexual homicide. Further, newer methods that have received attention in criminology, such as the machine learning method, were used to explore the ideal algorithm for classifying sexual homicide and patterns for sexual homicide in Korea. To do this, 542 homicide cases were analyzed utilizing eight algorithms, and the classification performance of each algorithm was analyzed along with the importance of variables. The results of the analysis revealed that the Naive Bayes, K-Nearest Neighbors, and RF algorithms demonstrate good classification accuracy, and generally, factors such as relationships, marriage, planning, personal weapons, and overkill were identified as crucial variables that distinguish sexual homicide in Korea. In addition, the crime scene information of the crime occurring in the dark (at night) and body disposal were found to have high importance. The current study proposes ways to enhance the efficacy of crime investigation and advance the research on sexual homicides in Korea through a more scientific understanding of sexual homicide that has not been thoroughly explored domestically.

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.

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.

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.

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.

Criminal Expertise and Sexual Violence: Comparing the Crime-Commission Process Involved in Sexual Burglary and Sexual Robbery.

Criminal expertise relates to the notion that some individuals may develop domain-specific offending skills that differentiate them from those with less skills or experience (i.e., novices). In the expertise literature, burglary has emerged as a distinct type of "expert" offense, therefore the current study sought to determine whether criminal expertise is more evident in the crime-commission process of sexual burglary compared to sexual robbery. We used binary logistic regression to compare the pre-crime, crime, and post-crime behaviors of 870 cases of hybrid sexual assault that occurred during the commission of either a burglary (N = 319) (or) robbery (N = 479), both of which involved personal theft from a stranger victim. Findings suggest that the crime commission process of sexual burglary involves a more sophisticated modus operandi and greater expertise in detection avoidance (e.g., strategies to protect their identity and destroying and removing evidence) compared to sexual robbery.

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.

Revenge filicide: An international perspective through 62 cases.

Filicide is the purposeful killing of one or more children by a parent, step-parent, or other parental figure. Revenge filicide is a poorly understood, rare form of filicide in which a parent murders their child to cause emotional harm to the child's other parent. This descriptive study presents an international case series consisting of 62 revenge filicide cases from nine countries. Perpetrators were about equally likely to be male or female. Over half of the sample had an active mental disorder of any type, most often a personality disorder. A history of domestic violence was common. The mean victim age was 6 years. They were typically killed by asphyxiation, firearms, or knives, and preschool age children were targeted most frequently. In half of the cases, more than one child was murdered. Post-crime suicidal behavior was commonplace, and one-third of the sample died by suicide. Four revenge filicide subtypes were identified: rejection, custody/visitation dispute, infidelity/jealousy, and argument/conflict. These categories may prove useful in future research and for helping to identify children at high risk of becoming filicide victims. All surviving offenders were criminally convicted, and in only one case was a mental health defense successful in lessening culpability. Notable similarities and differences between the US and international cases are discussed.

Elderly Sexual Abuse: An Examination of the Criminal Event.

The current study investigates the modus operandi specificities for the sexual abuse against the elderly. A comparison between sex crimes against adult and elderly victims is conducted following the criminal event approach. The comparison is based on the precrime, crime, and postcrime phases of the modus operandi, operationalized through 53 variables. The sample comes from a French national police database including a total of 1,829 cases-including 130 cases of elderly sexual abuse and 1,699 cases of sexual abuse against victims aged between 18 and 45 years. Bivariate and multivariate analyses are performed to examine the differences in the two groups. Several differences are observed between the two modus operandi. Findings indicate that the precrime phase is the most important to explain these differences, and this phase of the criminal event affects the rest of the decisions taken during the crime and postcrime phases. Specifically, we have highlighted that sexual crimes against the elderly are more violent and occur more often in the victim's residence. This study suggests that offenders targeting the elderly use specific crime characteristics, and this allows to highlight practical implications in terms of investigation and offender management.

Sexual Homicide: a Criminological Perspective.

PURPOSE OF REVIEW: This review presents recent findings of research focusing on sexual homicide. Firstly, we examine international comparative studies of victim, offender, and crime characteristics. Secondly, we review an important body of literature that compares developmental and psychological as well as the decision-making process of sexual murderers with other violent offenders. Thirdly, recent and major findings on links between sexual homicide and psychopathy as well as sadism are presented. Fourthly, findings on spatial behavior and factors that can explain it are discussed. Finally, the last section reviews characteristics of sexual homicide involving children and elderly victims. RECENT FINDINGS: International comparisons suggest that sexual homicide presents more similarities than differences across countries implying that most of knowledge can be generalized and applied to other countries. Comparisons with other types of violent offenders highlight that sexual murderers are a specific type of offenders with particular characteristics (criminal careers, developmental factors, personality disorders, lifestyle characteristics) and crime commission process (modus operandi, spatial behavior). As to the etiological factors of sexual homicide, psychopathy and sadism are important characteristics of sexual murderers leading their criminal life as well as their everyday life. Finally, studies focusing on specific types of vulnerable victims showed a high level of heterogeneity within the population of sexual murderers. Sexual murderers are specific offenders with peculiar characteristics and further research should develop proper knowledge on it. Creation of new international databases allows research to confirm and increase knowledge by considering sexual homicides as a complex heterogenous crime.

Lethal combinations: A conjunctive analysis of crime scene behavior associated with sexual homicide.

This research investigates violent stranger rapes and the factors leading these cases to sexual homicides. Variables relating to modus operandi characteristics on one part and offender behavior on the other part are examined using conjunctive analysis of cases configuration to identify the different combinations leading to a lethal outcome. Using a French sample of 1263 cases of violent rapes and 303 cases of sexual homicides involving female adult victims, we find that blows given by offenders and information about physical resistance of victims are strongly associated intentional and non-intentional sexual homicides. Psychoactive substance consumption by offenders as well associal isolation are in a lesser extend also associated with the lethal outcome.

Male and Female Single-Victim Sexual Homicide Offenders: Distinguishing the Types of Weapons Used in Killing Their Victims.

Most studies have focused on male sexual homicide offenders (SHOs) without testing whether sex differences exist. Accordingly, little is known about the distinctions between male and female SHOs, particularly with respect to their use of weapons in killing their victims. This study used a sample of 3,160 single-victim sexual homicide cases (3,009 male and 151 female offenders) from the U.S. Supplementary Homicide Reports database to explore sex differences in the types of murder weapons used by offenders in killing victims over the 37-year period 1976 to 2012. Findings indicated that significantly more male SHOs used personal weapons (43%) and more female SHOs used firearms (63%) in their offense commission. In general, female offenders predominantly used weapons that were physically less demanding (e.g., firearms and edged and other weapons; 89%). Different trends in the murder weapons used by male and female SHOs from different age groups were observed. Interestingly, findings showed that the type of weapon used by SHOs was in part influenced by the victims and their characteristics.

Sexual Murderers: Sex Offender, Murderer, or Both?

Sexual murderers perpetrate homicide and rape/sexual abuse, but it is unclear whether they should primarily be considered homicide offenders, sexual offenders, or both. Most studies have merged together different types of non-homicidal sex offenders (NHSOs), neglecting to consider the potential differences between the nonviolent and violent sex offenders. Here, we suggest it is important to isolate those violent sex offenders who inflict severe physical injuries that could potentially lead to a lethal outcome. Therefore, the aim of the current study is to compare different measures of the criminal career on three groups of sex offenders: NHSOs, violent NHSOs, and sexual homicide offenders (SHOs) using data from 616 incarcerated male sex offenders in a Federal penitentiary in Canada. Interestingly, the group of sex offenders with the worst criminal career profile was not the SHOs, but the violent NHSOs. Violent NHSOs had the greatest number of prior convictions and the most varied and versatile criminal career. Therefore, we suggest that based on their criminal career, SHOs should be considered more as murderers than sex offenders. However, to fully answer this question, future studies should include a group of non-sexual homicide offenders.

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.

Ligand-Stabilized Reduced-Dimensionality Perovskites.

Metal halide perovskites have rapidly advanced thin-film photovoltaic performance; as a result, the materials' observed instabilities urgently require a solution. Using density functional theory (DFT), we show that a low energy of formation, exacerbated in the presence of humidity, explains the propensity of perovskites to decompose back into their precursors. We find, also using DFT, that intercalation of phenylethylammonium between perovskite layers introduces quantitatively appreciable van der Waals interactions. These drive an increased formation energy and should therefore improve material stability. Here we report reduced-dimensionality (quasi-2D) perovskite films that exhibit improved stability while retaining the high performance of conventional three-dimensional perovskites. Continuous tuning of the dimensionality, as assessed using photophysical studies, is achieved by the choice of stoichiometry in materials synthesis. We achieve the first certified hysteresis-free solar power conversion in a planar perovskite solar cell, obtaining a 15.3% certified PCE, and observe greatly improved performance longevity.

Colloidal CdSe(1-x)S(x) Nanoplatelets with Narrow and Continuously-Tunable Electroluminescence.

Colloidal nanoplatelets, quasi-two-dimensional quantum wells, have recently been introduced as colloidal semiconductor materials with the narrowest known photoluminescence line width (∼10 nm). Unfortunately, these materials have not been shown to have continuously tunable emission but rather emit at discrete wavelengths that depend strictly on atomic-layer thickness. Herein, we report a new synthesis approach that overcomes this issue: by alloying CdSe colloidal nanoplatelets with CdS, we finely tune the emission spectrum while still leveraging atomic-scale thickness control. We proceed to demonstrate light-emitting diodes with sub-bandgap turn-on voltages (2.1 V for a device emitting at 2.4 eV) and the narrowest electroluminescence spectrum (FWHM ∼12.5 nm) reported for colloidal semiconductor LEDs.