Temporal and Spatial Analysis of Criminal Path of Different Types of Serial Sexual Offenders

摘要

Sexual violence is a global problem which causes social panic. This study focuses on analyzing the consistent spatial-temporal characteristics of serial sexual offenders and then further develops the future crime prevention strategies. This study scans over one thousand court judgments in Taiwan (2009 to 2012) and selects 39 serial sexual offenders who totally committed 114 cases. We collect several criminal characteristics, such as home-to-crime distances, step distance (crime-to-crime distance), offender's age, the relationship between offenders and victims (such as stranger rape, familiar rape and marital rape.), or even the transportation (travel mode) they used. The methodology of this research includes: 1) testing the temporal and spatial clustering of crime scenes via a revised Knox test, 2) evaluating the goodness-of-fit of offence trajectories with an animal movement model (such as the Levy walk model), and, (3) studying if spatial behaviors differ among various offenders and environmental factors. The results of this study can assist police in future investigations and the prevention of serial sex crimes. The results show that: (1) the distance between two continuous cases are usually shorter than 1 kilogram, because most crimes happened at offender's home or somewhere the offender familiar with. (2) The criminal moving pattern follows the Levy walk, which is a heavy-tailed distribution. In other words, crimes usually concentrate at specific place. (3) The travel distance is related to their travel mode and their relationship with victims. The results of this study can help the police authority predict the crime pattern and further achieve the purpose of crime prevention.