A qualitative analysis of mock jurors' deliberations of linkage analysis evidence

Evidence about a suspect's behavioural similarity across a series of crimes has been presented in legal proceedings in at least three different countries. Its admission as expert evidence, whilst still rare, is becoming more common thus it is important for us to understand how such evidence is received by jurors and legal professionals. This article reports on a qualitative analysis of mock jurors' deliberations about expert linkage analysis evidence. Three groups of mock jurors (N = 20) were presented with the prosecution's linkage analysis evidence from the USA State v. Fortin I murder trial and expert evidence for the defence constructed for the purposes of the study. Each group was asked to deliberate and reach a verdict. Deliberations were video‐recorded and subject to thematic content analysis. The themes that emerged were varied. Analysis suggested that the mock jurors were cautious of the expert evidence of behavioural similarity. In some cases they were sceptical of the expert. They articulated a preference that expert opinion be supported using statistics. Additional themes included jurors having misconceptions concerning what is typical offender behaviour during rape which suggests there is a need for expert linkage analysis evidence regarding behavioural similarities and the relative frequencies of crime scene behaviours. Copyright © 2010 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.     

An Exploration of Rapists' Motivations as Illustrated by Their Crime Scene Actions: Is the Gender of the Victim an Influential Factor?

An aim of this paper was to examine if the rapist's motivations of anger and power as inferred from rape crime scene behaviours differentiates between rape victim genders. In addition, it was sought to analyse the resistance strategies employed by rape victims to investigate whether gender influences victim–offender behavioural interactions. A sample of 24 female and 12 male rape victims aged from 13 to 39 years were analysed. The data were extracted from the US National Crime Survey, which contained 12 reported cases of male rape. It was hypothesised that the theme of power would be evident from the rapists' behaviour as illustrated by the crime scene actions and victim–offender interaction. Smallest Space Analysis, a multi‐dimensional scaling technique, was employed to identify the themes present in the perpetration of rape. The crime scene actions illustrated several distinctions relating to the theme of power present in the offender's motives irrespective of the victim's gender. An additional finding was that victim resistance strategies differentiated between male and female rape victims. Copyright © 2014 John Wiley & Sons, Ltd.     

Linking property crime using offender crime scene behaviour: A comparison of methods

This study compared the ability of seven statistical models to distinguish between linked and unlinked crimes. The seven models utilised geographical, temporal, and modus operandi information relating to residential burglaries (n = 180), commercial robberies, (n = 118), and car thefts (n = 376). Model performance was assessed using receiver operating characteristic analysis and by examining the success with which the seven models could successfully prioritise linked over unlinked crimes. The regression‐based and probabilistic models achieved comparable accuracy and were generally more accurate than the tree‐based models tested in this study. The Logistic algorithm achieved the highest area under the curve (AUC) for residential burglary (AUC = 0.903) and commercial robbery (AUC = 0.830) and the SimpleLogistic algorithm achieving the highest for car theft (AUC = 0.820). The findings also indicated that discrimination accuracy is maximised (in some situations) if behavioural domains are utilised rather than individual crime scene behaviours and that the AUC should not be used as the sole measure of accuracy in behavioural crime linkage research.     

Linking Crimes Using Behavioural Clues: Current Levels of Linking Accuracy and Strategies for Moving Forward

The number of published studies examining crime linkage analysis has grown rapidly over the last decade, to the point where a special issue of this journal has recently been dedicated to the topic. Many of these studies have used a particular measure (the area under the receiver operating characteristic curve, or the AUC) to quantify the degree to which it is possible to link crimes. This article reviews studies that have utilised the AUC and examines how good we are currently at linking crimes (within the context of these research studies) and what factors impact linking accuracy. The results of the review suggest that, in the majority of cases, moderate levels of linking accuracy are achieved. Of the various factors that have been examined that might impact linking accuracy, the three factors that appear to have the most significant impact are crime type, behavioural domain, and jurisdiction. We discuss how generalisable these results are to naturalistic investigative settings. We also highlight some of the important limitations of the linking studies that we reviewed and offer up some strategies for moving this area of research forward. 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.     

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.     

How does crime pay? The differentiation of criminal specialisms by fundamental incentive

Most attempts to determine offence specialisms have not benefited from any formal psychological framework of behavioural differentiation. Bandura's framework (Social foundations of thought and action, 1986) of the fundamental incentives to human action offers an interesting perspective on what might underlie differential patterns of offending. The framework draws attention to the distinction between Material, Power/Status, and Sensory incentives, leading to the hypotheses that crimes which share any one of these incentives will be more likely to be committed by the same person, as revealed through high inter‐correlations, but be less highly correlated with crimes with different fundamental incentives. To test these hypotheses the correlations between 42 offending behaviours as self‐reported by 185 convicted young offenders were examined. A Multidimensional Scaling analysis of the inter‐correlations revealed three distinct styles of offending that could be related to Bandura's Material (Cronbach's α = 0.94), Power/Status (α = 0.90) and Sensory (α = 0.76) incentives. The identification of this psychological basis for the differentiation of criminal styles provides a model for considering offenders' patterns of specialisation which is of value both in clarifying the aetiology of different types of crime and in considering which crimes may be behaviourally equivalent when trying to link them to a common offender or infer offender characteristics from crime scene information. Copyright © 2006 John Wiley & Sons, Ltd.     

Adult Missing Persons: Can an Investigative Framework be Generated Using Behavioural Themes?

There is a limited amount of research in the area of missing persons, especially adults. The aim of this research is to expand on the understanding of missing people, by examining adults' behaviours while missing and determining if distinct behavioural themes exist. Based on previous literature it was hypothesised that three behavioural themes will be present; dysfunctional, escape, and unintentional. Thirty‐six behaviours were coded from 362 missing person police reports and analysed using smallest space analysis (SSA). This produced a spatial representation of the behaviours, showing three distinct behavioural themes. Seventy percent of the adult missing person reports were classified under one dominant theme, 41% were ‘unintentional’, 18% were ‘dysfunctional’, and 11% were ‘escape’. The relationship between a missing person's dominant behavioural theme and their assigned risk level and demographic characteristics were also analysed. A significant association was found between the age, occupational status, whether they had any mental health issues, and the risk level assigned to the missing person; and their dominant behavioural theme. The findings are the first step in the development of a standardised checklist for a missing person investigation. This has implications on how practitioners prioritise missing adults, and interventions to prevent individuals from going missing. Copyright © 2016 John Wiley & Sons, Ltd.     

Improvement of Thematic Classification in Offender Profiling: Classifying Serbian Homicides Using Multiple Correspondence,Cluster, and Discriminant Function Analyses

This paper investigates thematic classification of homicides for the purpose of behavioural investigative analysis (e.g. offender profiling). Previous research has predominantly used smallest space analysis (SSA) to conceptualise and classify offences into thematic groups based on crime scene behaviour data. This paper introduces a combined approach utilising multiple correspondence analysis (MCA), cluster analysis (CA), and discriminant function analysis (DFA) to define and differentiate crime scenes into expressive or instrumental and impersonal or personal crimes. MCA is used to derive the latent structural dimensions in the crime data and produce quantitative scores for each offence along these dimensions. Two‐step CA was then utilised to classify offences. Offence dimensional scores were then used to predict cluster membership under DFA, producing cluster centroids corresponding to MCA dimensions. Centroids were plotted on the MCA correspondence map to simultaneously conceptualise crime classification and the latent structure of the Serbian crime data. Classification of offences based on MCA dimensional scores were 91.5% accurate. This MCA–CA–DFA approach may reduce some of the more subjective aspects of SSA methodology used in classification, whilst producing a product more amenable to objective and cumulative review. Implications for offender profiling research utilising SSA and this approach are discussed. Copyright © 2014 John Wiley & Sons, Ltd.     

Crime scene actions and offender characteristics in a sample of Finnish stranger rapes

The crime scene actions employed by offenders in stranger rapes were analysed in relation to offender characteristics. Data were drawn from an official police database and consisted of stranger rapes occurring in Finland between 1992 and 2001 (n = 100). The structure of dichotomous variables derived through a content analysis of crime scene actions and offender characteristics were analysed with non‐metric multidimensional scaling (MDS). The first analysis revealed three separate action themes, with thematic emphases on Hostility, Involvement or Theft. The MDS‐solution for offender characteristics suggested four themes: Conventional; Psychiatric/Elderly; Criminal/Violent; and Criminal/Property. Each case was assigned to one of the themes or as a hybrid in order to analyse the associations between action themes and characteristics. The only significant association was found between the action theme, Theft and characteristics theme Criminal/Property. The results are discussed in relation to previous research. Copyright © 2004 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.     

From marine ecology to crime analysis: Improving the detection of serial sexual offences using a taxonomic similarity measure

Jaccard has been the choice similarity metric in ecology and forensic psychology for comparison of sites or offences, by species or behaviour. This paper applies a more powerful hierarchical measure—taxonomic similarity (Δ_s), recently developed in marine ecology—to the task of behaviourally linking serial crime. Forensic case linkage attempts to identify behaviourally similar offences committed by the same unknown perpetrator (called linked offences). Δ_s considers progressively higher‐level taxa, such that two sites show some similarity even without shared species. We apply this index by analysing 55 specific offence behaviours classified hierarchically. The behaviours are taken from 16 sexual offences by seven juveniles where each offender committed two or more offences. We demonstrate that both Jaccard and Δ_s show linked offences to be significantly more similar than unlinked offences. With up to 20% of the specific behaviours removed in simulations, Δ_s is equally or more effective at distinguishing linked offences than where Jaccard uses a full data set. Moreover, Δ_s retains significant difference between linked and unlinked pairs, with up to 50% of the specific behaviours removed. As police decision‐making often depends upon incomplete data, Δ_s has clear advantages and its application may extend to other crime types. Copyright © 2007 John Wiley & Sons, Ltd.     

Content analysis of infanticide and neonaticide cases in the UK

Twenty cases, 14 infanticides and 6 neonaticides committed between 1989 and 2020 by biological mothers were analysed using Smallest Space Analysis for the presence of themes. Three themes associated with offender motivation were identified: Desperation, Disturbance and Rejection. Desperation theme included variables suggesting the mother committed the crime as a result of distress or perceived necessity. Disturbance suggested the motivation behind the offence to be as a result of the mother's caregiving role being disturbed; and the Rejection theme explained complete maternal rejection of the infant or new-born as the motivation behind the crime. Alongside the themes, three core variables were identified to be common for the crime regardless of motivation: the crime being committed at Home, the victim Female, and the crime being Denied by the mother. The implications of the findings are discussed including the potential for an investigative support tool and developing understandings of neonaticide and infanticide as separate crimes.     

Profiling Korean sex crimes: Offender characteristics and crime scene actions

The present study aimed to examine the demographic information of sex offenders in South Korea and explore whether a U.K. thematic model of criminal behaviour could be replicated in the Korean context. The 27 variables of crime scene actions derived from 50 Korean sexual offences through a content analysis were analysed with smallest space analysis. Chi‐square was also administered to explore the differences in offender characteristics among behavioural themes. Consequently, three separate action themes, hostility–involvement, theft, and control, were revealed. Next, each case was assigned to one of the dominant or hybrid themes, with 84% of the total cases being classified to the dominant themes. Moreover, there were significant differences in four offender characteristics between the themes: “previous conviction of robbery,” “previous conviction of sexual crime,” “knowing the victim,” and “vehicle use.” These outcomes have implications for the development of the Korean profiling system.     

Establishing the Duration of Crimes: An Individual Differences and Eye‐Tracking Investigation into Time Estimation

The time available for viewing a perpetrator at a crime scene predicts successful person recognition in subsequent identity line‐ups. This time is usually unknown and must be derived from eyewitnesses' duration estimates. This study therefore compared the estimates that different individuals provide for crimes. We then attempted to determine the accuracy of these durations by measuring observers' general time estimation ability with a set of estimator videos. Observers differed greatly in their ability to estimate time, but individual duration estimates correlated strongly for crime and estimator materials. This indicates that it might be possible to infer unknown durations of events, such as criminal incidents, from a person's ability to estimate known durations. We also measured observers' eye movements to a perpetrator during crimes. Only fixations on a perpetrator's face related to eyewitness accuracy, but these fixations did not correlate with exposure estimates for this person. The implications of these findings are discussed. Copyright © 2013 John Wiley & Sons, Ltd.     

The forgiveness process in primary and secondary victims of violent and sexual offences

It is possible that the physical and mental health of crime victims might be improved by forgiving those who have offended against them. To date, no research has been undertaken to examine the processes that influence victims' forgiveness. The goal of this project was to examine the forgiveness process in primary and secondary victims of violent and sexual crimes. In Study 1, qualitative data were collected by interviewing 21 people who had been affected by sexual or other violent crime. Data analysis identified five themes that were common to both primary and secondary victims, namely benefit of forgiveness, self‐forgiveness, perspective taking, offender behaviour, and time. An empowerment theme was unique to primary victims, and a principal victim theme was unique to secondary victims. To further explore these qualitative findings, a quantitative survey of 60 primary and secondary victims was conducted. Results confirmed that primary victims are pragmatic forgivers who are internally focused and forgive because that will benefit their healing. Conversely, secondary victims did not think forgiveness benefited, or would impact on, their own or the primary victim's recovery process. Neither group saw forgiveness as a moral issue, nor thought that forgiveness should influence whether an offender should face court.     

Investigating the nature of expressiveness in stranger,acquaintance and intrafamilial homicides

This study explores the role of the victim–offender relationship in the dynamics of homicide, by examining the crime scene behaviour of 25 intrafamilial, 30 acquaintance and 27 stranger homicide offenders (n = 82). Six crime scene variables were examined: ‘Weapon from the scene’, ‘Excessive wounding’, ‘Facial trauma’, ‘Multiple wounds to a single area’, ‘Post‐mortem activity’ and ‘Manual violence’. The first objective was to identify whether these variables could be combined to form a partially ordered scale of expressiveness. The second was to examine whether the nature of this expressive crime scene varied according to the victim and offender relationship. It was hypothesised that the intrafamilial homicides would be characterised by a more expressive crime scene. This was examined by Partial Order Scalogram Analysis which supported the hypothesised link between the level of expressed emotion evident in the crime scene and the nature of the victim–offender relationship. Further analysis on the individual variables revealed that the best single predictor of the relationship between victim and offender was the presence of multiple wounding. These findings are discussed both as contributing to a theoretical understanding of the emotional salience of crime scene actions when killing a family member, and in practical terms in relation to the significance of these variables for both police investigations and clinical interventions with homicide perpetrators. Copyright © 2005 John Wiley & Sons, Ltd.     

Instrumental and expressive violence in Belgian homicide perpetrators

The present study aimed to examine offender types in a sample of Belgian single‐perpetrator/single‐victim homicide cases. First, it was investigated if the distinction between instrumental and expressive aggression could be documented in crime scene and offender background characteristics. Second, the instrumental and expressive themes from the first analysis were examined in relation to the motives the perpetrators themselves provided for their offence. A sample of 97 solved homicide cases was analysed using the non‐metric multidimensional scaling procedure Proxscal. The results revealed that 62% of the homicide crime scenes and 67% of the offender backgrounds could be classified as either expressive or instrumental. The self‐reported motives did not correspond with the themes according to the Proxscal analysis. Copyright © 2010 John Wiley & Sons, Ltd.