  Drug sample comparison is a process used by the French National police to
identify drug distribution networks. The current approach is based on manual
comparison done by forensic experts. In this article, we present our approach
to acquire, formalise, and specify expert knowledge to improve the current
process. For modelling the underlying knowledge we use an ontology coupled with
logical rules. The different steps of our approach are designed to be reused in
other application domains. The results obtained are explainable making them
usable by experts in different fields.
