Precursor Events of Sex Crimes in Japan: A Spatio-Temporal Analysis of Reports of Contacts with Suspicious Persons by Target Age Groups

IntroductionPolice and other government agencies in Japan recognize that sex crimes targeting women and children are significant crime problems. Their increased efforts to protect these presumably vulnerable victims are clearly illustrated in national governmental reports and policies (Cabinet Council for Crime Control, 2005; National Police Agency, 2005, 2008). Although these reports and policies discuss a variety of crime prevention strategies, what is notable is that they list proactive policing of contacts with suspicious persons targeting children and women as the first crime control measure. That is, the proactive deployment of police officers and aggressive investigations of suspicious person reports are treated as the primary crime prevention tactic. In fact, the National Police Agency recently increased the number of police officers nationwide to create a taskforce that is responsible for such an approach (Cabinet Council for Crime Control, 2005; Daily Police News, 2009). The rationale behind such focused policing is that the reports of contacts with suspicious persons can be treated as precursor events of more serious sex crimes targeting children and women.Quite interestingly, however, the idea of contacts with suspicious persons as precursor events of sex crimes has never been examined empirically; the idea is a preconception and intuition at best among policy makers and the media. Therefore, in light of the lack of empirical evidence supporting the current police practice, this study examines whether or not reports of contacts with suspicious persons act as precursor events of future sex crimes by analyzing police data from a spatial and temporal perspective. In doing so, the current study contributes to criminological research both substantively and methodologically. The immediate policy implication of this study is its rigorous assessment of the validity of the current police practice in Japan. Additionally, by quantifying the spatial and temporal range of future sex crime risks, police departments can efficiently allocate their resources for focused police patrols. Furthermore, an empirical analysis of space-time clustering of crime incidents will deepen the understanding of criminal behavior and crime hot spot formation. In particular, an analysis of Japanese data presented for English audiences contributes to the body of criminological literature by confirming the universality of spatio-temporal clustering of crime incidents in a low crime nation. Finally, the study also makes a methodological contribution by extending an existing method of spatio-temporal crime analysis to a bivariate dimension with multiple crime types.As a guide to readers, the context of suspicious person reports in Japanese society should be explained. All 47 prefectural police departments have taskforces for crimes targeting women and children as noted above, and they collect and publish information about reports of encounters with suspicious persons on their websites. However, there is no uniform definition of what constitutes suspicious person reports, and the nature of incidents varies substantially. In order to analyze precursor events of predatory sex crimes, this paper limited its analysis to those incidents with actual verbal and/or physical contacts between the offender and victim; thus, simple observations of a suspicious person such as a suspected flasher, for example, are excluded. The encounters need to encompass either actual verbal communications (e.g., luring a child to a car, uttering words with sexual connotations) or minor physical interactions (e.g., grabbing a child by the arm, taking a photo or stalking). That is, the incidents that are analyzed in this study are those not serious enough to be considered as a crime but serious enough to have raised concerns among victims and their parents to report them to the authorities.Literature review: spatio-temporal analysis of crimeSubstantial spatial concentrations of crime incidents have been confirmed by empirical studies and have tremendous practical implications in policing and crime prevention activities. …