Serial Sexually Sadistic Murder and Robbery: Comparing Apples and Oranges?
Having explored the potential diversity within the supposedly same mode of crime (i.e., sexual assault), some consideration should also be afforded to generalizations that may be made across totally different modes of crime. Put simply, how valid are findings likely to be that are derived from a study examining homology among
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individuals who perpetrate robberies, for example, but thereafter are generalized and proposed to be relevant to the mechanisms and features said to characterize individu- als who perpetrate serial sadistic sexual murders?
The efficacy of such generalizations can first be considered by reference to the aforementioned cited literature concerning aberrant violent serial offenders such as that of, but not limited to, Hazelwood and Warren (1995); Schlesinger (2004, 2008); or Hickey (2012). In the authors’ opinion, a review of the subject literature suggests that limited similarities are likely to be found in the mental processes and mechanisms motivating the exhibited behaviors found in commercial robbers and, for example, serial sexually sadistic rapists or murderers. Indeed, the disparity between the mecha- nisms characteristic of offenders who perpetrate these differing modes of crime can also be seen in their criminological statistics. The phenomenon of serial murder con- stitutes approximately 1% of all recorded homicides in the United States (Federal Bureau of Investigation, 2008). However, the prevalence of robberies and burglaries in the United States vastly exceeds that of all recorded homicides let alone serial mur- ders.5 Although the criminal histories of some serial sexual murderers may feature, for example, the perpetration of crimes technically classified as burglary but typically motivated by fetish and/or voyeuristic goals (e.g., Hickey, 2012; Schlesinger & Revitch, 1999), the overwhelming majority of burglars and robbers do not engage in serial sexually sadistic murders. This suggests that while some sexual murderers may feature some behaviors and mechanisms roughly akin to those observed in burglars, the vast majority of offenders who perpetrate burglaries are not driven by the same mechanisms found among serial sexual murderers.
Moreover, research is available documenting the impact crime modality has upon the validity of theorems designed for criminal profiling. For example, in Kocsis and Irwin (1997), the efficacy of geographic profiling principles was concurrently exam- ined across samples of serial rapists, serial arsonists, and burglars. This study indicated that while the tested profiling principles were effective when applied to samples of rapists and arsonists, they were far less precise when applied to burglars. The contrast- ing variable in this study was crime modality6 and thus a comparison between the quite different inherent mechanisms associated with crimes of interpersonal violence such as rape and arson and those of criminal enterprise such as burglaries (see Kocsis, 2006a).
In summary, consideration of these factors suggests that research derived from offenders in quite disparate crime modalities such as, for example, robbery, will be of limited relevance with respect to their generalization to offenders who, for example, perpetrate serial sexually sadistic rapes or murders and, consequently, the profiling of such crimes.