Prioritizing patterns in evidence: Applying the analysis of competing hypotheses framework to criminal investigations and cold cases

Abstract

Police investigations often give rise to multiple hypothetical pathways for how the crime was conducted. Investigators may develop several hypotheses, often based on different pieces of evidence. It is often the case that investigators have too many potential hypotheses rather than too few. The current research shows a method of prioritizing hypotheses based on all evidence available and how this may help highlight and reduce bias in investigations. A real-world case of a homicide, that was originally misclassified as a death by natural causes is provided to show how Analysis of Competing Hypothesis (ACH) can be effectively used. Findings show support for the use of ACH in major crimes and cold case reviews. ACH allows investigators and reviewers to clearly show which hypotheses they have formulated and what evidence is consistent or inconsistent. In the case outlined, ACH may have led to consideration of poisoning rather than natural causes. This is the first paper to explore the use of ACH in major crimes and cold case reviews. While other authors have shown the importance of structuring decision making in police investigations, none have used the ACH framework.