Computer-Based Retrieval of Suspects Using Similarity of <i>Modus Operandi</i>

Abstract

This report presents the development and evaluation of the suspect retrieval system based on modus operandi developed by the National Research Institute of Police Science in Japan. The database used in the system stores a large number of records consisting of the modus operandi of prior offenders. A score is assigned to each record, where each score represents the similarity of the modus operandi between each record and a crime under investigation. The similarity is statistically calculated based on the choice probability of each modus operandi. Suspects in the database are rank ordered according to scores. The higher a rank is, the more likely a suspect is expected to have committed the crime under investigation. The validity of the system is evaluated with data about Japanese burglars (n = 12,468) and some factors influencing the accuracy of the retrieval are discussed.