In this forensics activity, learners solve a mystery using “DNA” taken from the scene of the crime. This activity describes how to collect a “DNA sample” (learner-invented DNA sequence on a roll of paper) from the culprit and from each learner in the group, then run the DNA on a “gel” that covers the floor of the classroom, a hallway, or gymnasium. The crime-scene investigation aspect can become as elaborate as you wish by including additional “clues” such as fingerprints, a ransom note written in a specific type of ink, cloth fibers, eyewitness accounts and more. [Activity is publicly available through a web crawler capture on Archive.org.]