Identifying contributors of two-person DNA mixtures by familial database search

The role of familial database search as a crime-solving tool has been increasingly recognized by forensic scientists. As an enhancement to the existing familial search approach on single source cases, this article presents our current progress in exploring the potential use of familial search to mixture cases. A novel method was established to predict the outcome of the search, from which a simple strategy for determining an appropriate scale of investigation by the police force is developed. Illustrated by an example using Swedish data, our approach is shown to have the potential for assisting the police force to decide on the scale of investigation, thereby achieving desirable crime-solving rate with reasonable cost.