Unfolding crime scenarios with variations: a method for building a Bayesian network for legal narratives

Legal reasoning can be approached from various perspectives, traditionally argumentation, probability and narrative. The communication between forensic experts and a judge or jury would benefit from an integration of these approaches. In previous papers we worked on the connection between the narrative and the probabilistic approach. We developed techniques for representing crime scenarios in a Bayesian network. But for complex cases, the construction of a Bayesian network structure using these techniques remained a cumbersome task. In this paper we therefore propose a method called unfolding a scenario and a representation for small variations within a scenario. With these tools, a Bayesian network can be built up step by step, gradually adding more details. The method of unfolding a scenario is intended to support the process of building a Bayesian network, additionally resulting in a well-structured graphical structure