Potential violent criminals will often need to go through a sequence of preparatory steps before they can execute their plans. During this escalation process police have the opportunity to evaluate the threat posed by such people through what they know, observe and learn from intelligence reports about their activities. In this paper we customise a three-level Bayesian hierarchical model to describe this process. This is able to propagate both routine and unexpected evidence in real time. We discuss how to set up such a model so that it calibrates to domain expert judgments. The model illustrations include a hypothetical example based on a potential vehicle based terrorist attack.
This work was funded by The Alan Turing Institute Defence and Security Project G027. We are grateful for the comments of two anonymous referees and the associate editor which greatly improved this paper.
"A Bayesian Hierarchical Model for Criminal Investigations." Bayesian Anal. 16 (1) 1 - 30, March 2021. https://doi.org/10.1214/19-BA1192