Unravelling Crime Series Patterns amongst Serial Sex Offenders: Duration,Frequency, and Environmental Consistency

Crime linkage and the investigation of behavioural consistency amongst serial offenders has been a flourishing field of research over the past decade or so, especially with respect to serial sex offenders. The emerging research in this field has often portrayed serial sex offenders as a single, distinct, and homogeneous group. Such an assumption, however, has never been empirically examined. Using a criminal career approach and a sample of 72 serial sex offenders who have committed a total of 361 sexual assaults on stranger victims, the current study aims to examine and describe subgroups of crime series patterns amongst serial sex offenders in terms of duration and frequency of offending. The level of environmental consistency display (i.e. offender's choice of crime location and characteristics of the crime site selected) across subgroups of crime series patterns is also examined. Study findings suggest the presence and heterogeneity of crime series patterns amongst serial sex offenders, advocating for the consideration of subgroups of crime series patterns when studying serial sex offenders. Moreover, the offenders' level of environmental consistency varies across the different crime series patterns identified, allowing for the identification of subgroups of offenders showing a higher or lower level of environmental consistency. Copyright © 2014 John Wiley & Sons, Ltd.     

South African Serial Homicide: Consistency in Victim Types and Crime Scene Actions Across Series

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.     

South African Serial Homicide: Offender and Victim Demographics and Crime Scene Actions

There is an abundance of literature on serial homicide from a Western perspective that outlines operational definitions, types of offenders and how they prey upon their victims. However, currently, there is a lack of studies that compare serial homicide in different countries. The current study aims to give an overview of the demographics of serial homicide offenders and victims in South Africa and compare these to the demographics of offenders and victims from other currently available empirical studies of other countries. The sample consisted of 33 out of the total 54 solved series in South Africa between 1936–2007, which includes a total of 33 offenders, 302 victims, and 254 crime scenes. Results of the sample as a whole showed that South African serial homicide offenders are similar to offenders in other countries in terms of their actions at the crime scene and victim choice, with some notable exceptions. Additional analysis looked at the offender's consistency of targeting certain types of victims across their homicide series in comparison with the patterns of serial homicide offenders in other countries. Copyright © 2014 John Wiley & Sons, Ltd.     

An examination of behavioral consistency using individual behaviors or groups of behaviors in serial 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.     

Offending Patterns of Serial Sex Offenders: Escalation,De‐escalation,and Consistency of Sexually Intrusive and Violent Behaviours

A series of stranger sexual assaults poses considerable obstacles for law enforcement officials. One such preoccupation is concerned with whether or not the offender will escalate in the severity of his behaviours with subsequent victims. The current study uses transition matrices to address whether or not the offending patterns of 72 serial stranger sex offenders change from one victim to the next as it pertains to their sexual acts and level of physical force used during the crime. Findings indicate that stability, specifically the offender's intrusive sexual acts and use of physical force, and versatility are present in this sample's offending patterns. To explain changes in offending patterns between victims, multinomial regression analyses indicate that situational factors and modus operandi strategies are important considerations. Implications for investigations are discussed. Copyright © 2013 John Wiley & Sons, Ltd.     

Linking serial residential burglary: comparing the utility of modus operandi behaviours,geographical proximity,and temporal proximity

Whilst case linkage is used with serious forms of serial crime (e.g. rape and murder), the potential exists for it to be used with volume crime. This study replicates and extends previous research on the behavioural linking of burglaries. One hundred and sixty solved residential burglaries were sampled from a British police force. From these, 80 linked crime pairs (committed by the same serial offender) and 80 unlinked crime pairs (committed by two different serial offenders) were created. Following the methodology used by previous researchers, the behavioural similarity, geographical proximity, and temporal proximity of linked crime pairs were compared with those of unlinked crime pairs. Geographical and temporal proximity possessed a high degree of predictive accuracy in distinguishing linked from unlinked pairs as assessed by logistic regression and receiver operating characteristic analyses. Comparatively, other traditional modus operandi behaviours showed less potential for linkage. Whilst personality psychology literature has suggested we might expect to find a relationship between temporal proximity and behavioural consistency, such a relationship was not observed. Copyright © 2010 John Wiley & Sons, Ltd.     

Serial homicide: an investigation of behavioural consistency

To examine if serial homicide offenders are consistent across their crimes, a model was developed empirically that could be used to distinguish between crimes that were instrumental and those that were expressive. The first known three offences in each series of 69 US serial homicides committed by 23 offenders, were examined and the instrumental and expressive themes determined. Three models were then explored that test for consistency across these themes. The most liberal model was found to classify all of the offences effectively and to reveal complete consistency across the three crimes for all offenders. The implications of these results for offender profiling and further study of serial homicide are discussed. Copyright © 2005 John Wiley & Sons, Ltd.     

Comparing the Predictive Accuracy of Case Linkage Methods in Serious Sexual Assaults

The empirical support for linkage analysis is steadily increasing, but the question remains as to what method of linking is the most effective. We compared a more theory‐based, dimensional behavioural approach with a rather pragmatic, multivariate behavioural approach with regard to their accuracy in linking serial sexual assaults in a UK sample of serial sexual assaults (n = 90) and one‐off sexual assaults (n = 129). Their respective linkage accuracy was assessed by (1) using seven dimensions derived by non‐parametric Mokken scale analysis (MSA) as predictors in discriminant function analysis (DFA) and (2) 46 crime scene characteristics simultaneously in a naive Bayesian classifier (NBC). The dimensional scales predicted 28.9% of the series correctly, whereas the NBC correctly identified 34.5% of the series. However, a subsequent inclusion of non‐serial offences in the target group decreased the amount of correct links in the dimensional approach (MSA–DFA: 8.9%; NBC: 32.2%). Receiver operating characteristic analysis was used as a more objective comparison of the two methods under both conditions, confirming that each achieved good accuracies (AUCs = .74–.89), but the NBC performed significantly better than the dimensional approach. The consequences for the practical implementation in behavioural case linkage are discussed. Copyright © 2012 John Wiley & Sons, Ltd.     

South African Serial Homicide: A Victim‐Focused Behavioural Typology

This current study assessed the value of the Interpersonal Model in differentiating serial homicide offences in South Africa, notably in terms of how the offender may display behavioural patterns that are indicative of them dealing with the victim as a Person, an Object, or a Vehicle. The sample consisted of 302 offences committed by 33 offenders that occurred from 1953 to 2007 in South Africa. Multidimensional scaling analysis was used to test the Interpersonal Model and results indicated that crime themes did not directly correspond to the threefold model. Instead, two crime scene types were present: Victim as Object (where the focus was on tangible gains, interaction with the victim throughout the phases of the crime was limited, and victims included men and live women) and Victim as Vehicle (where the victim might be construed as a conduit through whom the offender could realise their specific psychological needs, the interaction was extensive, and victims tended to be vulnerable). South African serial homicides did not appear to have a specific sub‐theme of Victim as Person, suggesting that the themes engaged in centred more on instrumentally focused actions but in qualitatively different ways. However, victim types were integral to the overall behavioural model. Using the Victim as Object/Vehicle dichotomy, 85.7% of the offences could be seen to engage dominantly in one of the two patterns at the crime scene. This not only supported the results of a twofold model, but having these many offenders showing a dominant crime scene type also shows that the model is an excellent representation of serial homicide offending in South Africa. Copyright © 2014 John Wiley & Sons, Ltd.     

Between a ROC and a hard place: a method for linking serial burglaries by modus operandi

The purpose of this study is to determine if readily available information about commercial and residential serial burglaries, in the form of the offender's modus operandi, provides a statistically significant basis for accurately linking crimes committed by the same offender. Logistic regression analysis is applied to examine the degree to which various linking features can be used to discriminate between linked and unlinked burglaries. Receiver operating characteristic (ROC) analysis is then performed to calibrate the validity of these features and to identify optimal decision thresholds for linking purposes. Contrary to crime scene behaviours traditionally examined to link serial burglaries, the distance between crime site locations demonstrated significantly greater effectiveness as a linking feature for both commercial and residential burglaries. Specifically, shorter distances between crimes signalled an increased likelihood that burglaries were linked. Thus, these results indicate that, if one examines suitable behavioural domains, high levels of stability and distinctiveness exist in the actions of serial burglars, and these actions can be used to accurately link crimes committed by the same offender. Copyright © 2005 John Wiley & Sons, Ltd.     

Examining the Role of Similarity Coefficients and the Value of Behavioural Themes in Attempts to Link Serial Arson Offences

When relying on crime scene behaviours to link serial crimes, linking accuracy may be influenced by the measure used to assess across‐crime similarity and the types of behaviours included in the analysis. To examine these issues, the present study compared the level of linking accuracy achieved by using the simple matching index (S) to that of the commonly used Jaccard's coefficient (J) across themes of arson behaviour. The data consisted of 42 crime scene behaviours, separated into three behavioural themes, which were exhibited by 37 offenders across 114 solved arsons. The results of logistic regression and receiver operating characteristic analysis indicate that, with the exception of one theme where S was more effective than J at discriminating between linked and unlinked crimes, no significant differences emerged between the two similarity measures. In addition, our results suggest that thematically unrelated behaviours can be used to link crimes with the same degree of accuracy as thematically related behaviours, potentially calling into the question the importance of theme‐based approaches to behavioural linkage analysis. Copyright © 2012 John Wiley & Sons, Ltd.     

Development of serial processing in reading and rapid naming

Serial rapid automatized naming (RAN) is more strongly related to reading fluency than naming of isolated words, suggesting that the implementation of serial processing may underlie the RAN–reading relationship. In this study, 107 Greek children from Grade 2 and 107 from Grade 6 were tested with discrete and serial naming of digits, objects, and words in 50-item arrays. The correlation between discrete and serial word reading was very high in Grade 2 but only moderate in Grade 6. In confirmatory factor analysis, a reading–naming latent structure fit the Grade 2 data best; in contrast, a serial–discrete structure fit the Grade 6 data. Thus, the superficial longitudinal stability of RAN–reading correlations belies vastly different patterns of interrelations, indicative of changes in the developing cognitive processes underlying both naming and reading. Word fluency tasks in Grade 2 are apparently accomplished largely as a series of isolated individual word naming trials even though multiple individual letters in each word may be processed in parallel. In contrast, specifically serial procedures are applied in Grade 6, presumably via simultaneous processing of multiple individual words at successive levels. It is proposed that this feat requires endogenous control of cognitive cascades.     

Risk behaviour and mental workload: Multimodal assessment techniques applied to motorbike riding simulation

We present data from an ongoing research project on the cognitive, emotional and neuropsychological basis of risk behaviour. The main aim of the project is to build a model of risk behaviour so that if we know certain cognitive, behavioural and emotional variables, we will be able to predict decisions made in the face of uncertainty and risk, with the final goal of designing programs for evaluating, preventing and controlling risk behaviour. The objective of the present study was to look for individual differences in hazard perception during a static riding simulation and their relationship with mental workload. We used a multidimensional methodology, including behavioural, subjective and physiological data. The behavioural measures were obtained in a static riding simulation during eight hazard situations. We evaluated whether eye activity measures correlated with cognitive workload and different types of risky behaviours. Eye movement parameters were measured using a video-based eye tracking system. We found that risk-prone individuals showed specific patterns of risky behaviours and that peak of saccadic velocity and subjective mental workload indexes were both reliable indicators of risk proneness. Mental workload was higher for participants showing attitudes to risk behaviours probably because of a lack of conscious awareness of specific cues indicating dangerous scenarios.     

Distance patterns and disposal sites in rural area homicides committed in Finland

The present study examined offender characteristics, distance patterns, and the nature of disposal sites in rural area homicides. Pre‐trial investigation files of cases where victims' bodies were found in rural areas in 1994–2005 (n = 46) and forensic psychiatric examination reports of the offenders were content‐analysed. Psychopathy Check List‐Revised was used to assess psychopathy. Investigators of these homicides filled out a questionnaire on the offender's familiarity with the body disposal area, and MapInfo was used to measure offender/victim‐residence‐to‐crime‐to‐body‐disposal‐site distances. Rural area homicides more frequently involved multiple offenders who were significantly younger than offenders in other homicides. Of the victims, 73% were found in woods and 27% in water. Offenders were familiar with disposal sites in over half of the cases. The victim's gender, close relationship with the offender, and the offender's violent crime history were associated with longer homicide‐scene‐to‐body‐disposal‐site distances. The number of inhabitants and offender's violent crime history were related to longer offender‐residence‐to‐body‐disposal‐site distances. Offender's age, intelligence, or psychopathology bore no significant association with the distance patterns. The results can be applied when searching missing persons in homicide investigations and in prioritising suspects in rural area homicides. Copyright © 2008 John Wiley & Sons, Ltd.     

The effect of strength of cognitive linkages on attitude change in a communication situation

Implicitly or explicitly, linkage is a basic concept in all theories of cognitive consistency — consistency or inconsistency can exist only with reference to entities which are cognitively linked through association or dissociation. The nature of cognitive linkages has not been systematically studied, but it seems evident that they may vary in many ways. One is the strength or intensity of perceived relationship between cognitive entities. The basic hypothesis in the present two experiments was that the effect of a communication in terms of attitude change would depend on the strength of linkage between concepts mentioned in the message. Results show no such effect when strength was manipulated through combination of linkages, whereas the hypothesis was confirmed when linkage strength was varied semantically. Also, previous studies on direct and mediated generalization of attitude change towards consistency were successfully replicated. Finally, it was found that amount of attitude change towards consistency was significantly higher for linkages involving affect (L-relations) than for linkages simply expressing unit formation (U-relations).     

Healthcare Serial Killers as Confidence Men

Although there is adequate coverage of serial murder in the extant homicide literature, there is a lack of systematic examination of healthcare professionals who serially murder their patients. Using a sample of 58 healthcare serial killers located within North America, South America, and Europe between the years of 1970 and 2010, this study examines notable pre‐offense and post‐offense behaviours of healthcare serial killers. Patterns related to offender aetiology, victim cultivation, crime scene behaviour, and techniques of evasion were explored. The findings from this study suggest that the pre‐offense and post‐offense behaviours of healthcare serial killers can be conceptualised from the theoretical framework of confidence men or ‘con men’. The findings from this study also suggest that healthcare serial killings and offenders who perpetrate them continue to be elusive and warrant additional scholarly attention to reduce their likelihood of engaging in homicide undetected for extended time. Policy implications are also discussed. Copyright © 2013 John Wiley & Sons, Ltd.     

Growth mixture modelling in developmental psychology: overview and demonstration of heterogeneity in developmental trajectories of adolescent antisocial behaviour

Recent advances in statistical techniques for longitudinal data analysis have provided increased capabilities for elucidating individual differences in trajectories of change in child behaviours and abilities. However, most techniques still assume that there is a single underlying distribution with respect to changes over time, about which children are normally distributed. If there are multiple subgroups of youth following distinct developmental trajectories with unique predictors, however, the results of these statistical techniques may provide an incomplete analysis of the data. A newer class of statistical techniques, latent growth mixture modelling, provides a robust framework for examining heterogeneity in patterns of development. This paper illustrates the use of latent growth mixture modelling for examining heterogeneity in developmental trajectories of adolescent antisocial behaviour. Copyright © 2006 John Wiley & Sons, Ltd.     

Effects of containment and closure policies on controlling the COVID‐19 pandemic in East Asia

Growing efforts have been made to pool coronavirus data and control measures from countries and regions to compare the effectiveness of government policies. We examine whether these strategies can explain East Asia’s effective control of the COVID‐19 pandemic based on time‐series data with cross‐correlations between the Stringency Index and number of confirmed cases during the early period of outbreaks. We suggest that multidisciplinary empirical research in healthcare and social sciences, personality, and social psychology is needed for a clear understanding of how cultural values, social norms, and individual predispositions interact with policy to affect life‐saving behavioural changes in different societies.     

Comparing single and serial homicide offenses

Serial homicide has attracted much attention, but little empirical scientific investigation. This exploratory study reports demographic information on a large sample of serial homicide offenders (157 offenders, 608 victims), and compares a subsample of serial homicide offenses with a control group of single homicide offenses. Results show that serial homicide offenders target more women than men, and kill more strangers than family or friends. Single homicide offenders kill men and women in equal frequency, but kill family and friends more often than strangers. Serial homicide offenders kill for apparent sexual motivation more often than for any other reason, while single homicide offenders kill most often out of anger.