Serial sex offenders’ environmental consistency and crime site selection across series

Crime linkage analysis constitutes a potential tool to help investigators prioritize suspects in cases of serial crimes. While crime linkage has been a burgeoning field of research for the last decade or so, a still scarce amount of research limits our knowledge on environmental consistency among serial sex offenders. Furthermore, methodological issues characterize previous studies on consistency. The current dissertation departs from previous studies in the crime linkage field by building on research coming from the criminal career field in order to move forward research on serial sex offenders’ environmental consistency and crime site selection. To this end, it is organized into three separate but related empirical studies. The first study examined consistency for specific geographic and environmental factors using various coefficients, two of them taken from the criminal career literature. While a high level of consistency was found, some environmental aspects of the crime showed better consistency than others, making them more valuable for crime linkage analysis. Findings also indicated on the bias associated with each coefficient and the potential contribution of coefficients from the criminal career field when measuring offenders’ consistency. In the second study, environmental consistency was further explored using a crime-event approach. More specifically, crime sites used by serial sex offenders were investigated across series to examine for their stability. Distinct and recurrent crimes sites used across series were identified, indicating that serial sex offenders operate over limited environments. In addition, preliminary data suggesting that a connection exists between the victim encounter site selected and the offender’s series progression was provided. More specifically, the use of sites known to “attract” potential victims decreased over series and offenders became more risk-taking in regard to sites selected to encounter their victims. In the third study, heterogeneity among serial sex offenders, with regard to offending frequency and duration, was assessed. Findings indicated that different crime series patterns were present, such patterns significantly influencing offenders’ levels of consistency. Taken together, the results of these three studies high¬lighted heterogeneity of serial sex offenders’ crime series patterns while demonstrating the relationship and stability between their past and future environmental behaviors.