Classifying Serial Sexual Murder/Murderers

Abstract

Keppel and Walter's (1999) classification system for serial sexual murder/murderers is sometimes used as the basis for generating offender profiles despite the fact that it has yet to be empirically validated. This model assumes that serial sexual murder/murderers can be classified into four categories-power-assertive, power-reassurance, anger-retaliation, and angerexcitation-according to the degree of anger and power exhibited by the offender in their criminal and noncriminal lives. Within the current study, assessing the validity of this model involved examining the crimes and backgrounds of 53 serial sexual murderers to determine if the categories proposed by Keppel and Walter could be identified. Proximity Scaling was used to examine the degree of co-occurrence between each and every behavior/characteristic. no evidence of highly cooccurring behaviors/characteristics from Keppel and Walter's proposed categories was found, indicating that the classification system is potentially invalid. results are discussed in terms of their theoretical and practical implications.

The utility of latent variable models in refining behavioural crime scene analysis of serial stranger sexual offences

“…Motivation cannot be directly observed from the crime, the offenders' reports, victim report, or any other source of objective data and must, therefore, be inferred (Canter et al, 2003). Groth and Birnbaum's typology was largely constructed and refined using case evidence and clinical opinion, rather than statistical modeling; and despite some recent research using MDS to statistically investigate aspects of the typology (Bennell et al, 2013;, case-based research still dominates the evaluation of Groth and Birnbaum's model (Pardue & Arrigo, 2008;Salfati & Taylor, 2006).…”

“…Previous researchers (Alison, Bennell, Mokros, & Ormerod, 2002;Bennell et al, 2013;Dietz, Hazelwood, & Warren, 1990;Proulx, Blais, & Beauregard, 2005;Ressler & Shachtman, 1992;Warren, Hazelwood, & Dietz, 1996) have identified a number of crime scene behaviours relevant to sadism, such as torture, binding victims blindfolded or gagged, kidnapping, humiliation, torture, asphyxiation as primary means of death, trophies collected, foreign object penetration, use of a rape kit, and postmortem sexual acts or mutilation.…”

“…If the focus of the study is on similarities (as compared to differences) between variables, one must select the MDS PROXSCAL function (Busing, Commandeur, & Heiser, 1997;Commandeur & Heiser, 1993) as the MDS ALSCAL feature (Takane, Young, & de Leeuw, 1977) is based on a dissimilarity matrix and will thus lead to erroneous findings (Goodwill, Alison, & Humann, 2009;Sturidsson et al, 2006). While various measures of association have been used in previous BCSA research, e.g., the Bray-Curtis coefficient (Bennell et al, 2013;Santtila, Korpela, & Häkkänen, 2004), the Jaccard's measure is the most common one in BCSA research (Lehmann et al, 2013). The Jaccard's measure (also known as Jaccard's Index or similarity coefficient) was developed by Paul Jaccard (1901) to measure similarity and diversity in samples.…”

Characteristics of Sexual Homicide Offenders Focusing on Child Victims: A Review of the Literature

“… Keppel and Walter (1999) expanded these typologies to include crime scene behaviors and background characteristics that may indicate which type of killer committed the homicide. However, when Bennell et al (2013) attempted to validate Keppel and Walter’s (1999) model, they did not find any evidence to support the four types.…”

Understanding the variation in offender behaviour and risk factors in cases of homicide perpetrated against the UK homeless population between the years 2000 and 2022

“…This model has been repeatedly tested and applied across a multitude of crime types including serial homicide (Hodge, 2000), sexually motivated homicide (Bennell et al., 2013), and human trafficking (Ioannou & Oostinga, 2015).…”