One “Two” Many: An Examination of Solo Perpetrator Versus Team Perpetrator Serial Homicides

The current study examines the offender, victim, and crime characteristics between solo perpetrators and team perpetrators of serial homicide. Cases on 1,137 solo perpetrators and 254 team perpetrators were collected from the Consolidated Serial Homicide Offender Database. Results showed team perpetrators were more likely to be older than those who committed serial homicides alone. Offenders who never confessed their crimes were less likely to participate in teams. In terms of victim and crime characteristics, team perpetrators were more likely to target employees or customers, have a lower victim count, and were more likely to exhibit sadistic behaviors compared to solo perpetrators. Theoretical and practical implications from this study are discussed.

A Scoping Review of Serial Homicide Geographic Mobility Literature and Four Typologies

The study of geographic mobility through geospatial analysis and journey-to-crime approaches has made progress in environmental criminology, finding most offenders commit crime close to their residence. However, extant literature on serial homicide and geographic mobility is scarce, specifically lacking a comprehensive appraisal of relative research. To gain a better understanding of the geographic mobility patterns of serial homicide offenders, we must determine the current status of literature in this area, to figure out where to go in terms of future research. Therefore, the following study is a scoping review of existing literature on geographic mobility and serial homicide and four associated typologies (Holmes & DeBurger’s Geographic typology, Hickey’s Mobility typology, Canter’s Circle typology, and Rossmo’s Hunting Style typology) to achieve the following: (1) Comprehensively evaluate literature regarding serial homicide geographic mobility and four associated typologies to establish the current status of research; (2) uncover potential literature gaps; and (3) provide future research recommendations. Literature sources ( N = 43) on serial homicide and geographic mobility (1985–2018) were examined. While findings recognize the relevance of mobility functions in serial homicide investigations, gaps in literature were evident regarding serial homicide geographic mobility and the four associated typologies. Findings also reveal that systematic research in this field is limited. Policy implications and future research recommendations are discussed.

Linking serial homicide – towards an ecologically valid application

Purpose Crime linkage analysis (CLA) can be applied in the police investigation-phase to sift through a database to find behaviorally similar cases to the one under investigation and in the trial-phase to try to prove that the perpetrator of two or more offences is the same, by showing similarity and distinctiveness in the offences. Lately, research has moved toward more naturalistic settings, analyzing data sets that are as similar to actual crime databases as possible. One such step has been to include one-off offences in the data sets, but this has not yet been done with homicide. The purpose of this paper is to investigate how linking accuracy of serial homicide is affected as a function of added hard-to-solve one-off offences. Design/methodology/approach A sample (N = 117–1160) of Italian serial homicides (n = 116) and hard-to-solve one-off homicides (n = 1–1044, simulated from 45 cases) was analyzed using a Bayesian approach to identify series membership, and a case by case comparison of similarity using Jaccard’s coefficient. Linking accuracy was evaluated using receiver operating characteristics and by examining the sensitivity and specificity of the model. Findings After an initial dip in linking accuracy (as measured by the AUC), the accuracy increased as more one-offs were added to the data. While adding one-offs made it easier to identify correct series (increased sensitivity), there was an increase in false positives (decreased specificity) in the linkage decisions. When rank ordering cases according to similarity, linkage accuracy was affected negatively as a function of added non-serial cases. Practical implications While using a more natural data set, in terms of adding a significant portion of non-serial homicides into the mix, does introduce error into the linkage decision, the authors conclude that taken overall, the findings still support the validity of CLA in practice. Originality/value This is the first crime linkage study on homicide to investigate how linking accuracy is affected as a function of non-serial cases being introduced into the data.

Detecting a Decline in Serial Homicide: Have We Banished the Devil from the Details?

Objectives: The likelihood that serial murderers are responsible for most unresolved homicides and missing persons was examined by investigating the accounting of the phenomenon in the context of a declining prevalence. Methods: A mixed methods approach was used, consisting of a review of a sample of unresolved homicides, a comparative analysis of the frequency of known serial homicide series and unresolved serial homicide series, and semi-structured interviews of experts.Results: The past decade contained almost half the cases (13%) that existed at the 1980s peak of serial homicide (27%). Only 282 (1.3%) strangled females made up the 22,444 unresolved homicides reviewed. Most expert respondents thought it unreasonable that any meaningful proportion of missing persons cases are victims of serial homicide. Conclusions: Technology, shifts in offending behavior, proactive law enforcement action, and vigilance of society have transformed serial killing and aids in viewing offenders as people impacted by societal shifts and cultural norms. The absence of narrative details inhibited some aspects of the review. An exhaustive list of known unresolved serial homicide series remained elusive as some missing persons are never reported. Future research should incorporate those intending to murder serially, but whose efforts were stalled by arrest, imprisonment, or death.

Exploring the Similarities and Differences in Offender Characteristics Across Aspiring, Probable, and Successful Serial Homicide Offenders: The Importance of an Inclusive Approach to the Study of Homicide

The current study examines potential serial homicide offenders (SHOs), a previously unacknowledged offender group comprised of aspiring and probable SHOs, and compares them to successful SHOs. Data on 17 aspiring, 46 probable, and 16 successful SHOs were collected. The study results indicate that potential serial killers share more in common with successful SHOs than they do with one-off homicide offenders. While there is overlap among these groups, there is insufficient evidence to suggest discreet transitions among categories or that being a potential SHO is the final step on a pathway towards becoming a successful SHO. Potential SHOs cannot reliably be thought of as prospective SHOs if all things were equal. An as yet identified factor, such as resiliency, still separates potential SHOs from successful SHOs. Early identification and timely intervention is important to interrupt impending murders by potential SHOs and halt them at this pivotal point in their developmental trajectory.