This document provides an overview for a molecular murder mystery activity where students will work in groups to identify substances bound to the active site of cytochrome c oxidase using 3D protein structures downloaded from an online source. Background information is given on the protein including its normal function of reducing oxygen to water. Students will develop a mystery story and use online resources to deduce what is bound to different protein structures. The goal is to help students learn while practicing skills for identifying elements and active sites in proteins.