Crime Linkage: Finding a Behavioral Fingerprint Using the “Path Similarity Metric”

When a detective arrives at a crime scene, or investigates multiple cases, they are often tasked with understanding whether the crimes are linked. Knowing whether the same suspect(s) was involved across multiple crimes is a key part of the investigation. To date, there are numerous methods for crime linkage; however, very few take temporal sequences of events into account. It is known that modus operandi and signatures change over time, and therefore, linkage analyses should integrate these temporal changes. The current paper presents a new method of crime linkage, the Path Similarity Metric, which is based on sequence analysis procedures. The method is proposed, outlined, and tested in contrast to existing linkage analyses (e.g., Jaccard’s coefficient). The Path Similarity Metric outperforms Jaccard’s coefficient across a series of crimes. Future applications of the Path Similarity Metric are outlined, and directions for the use of the metric in ongoing investigations are considered alongside other linkage methods.