CSI: Crime Scene Investigation (2000) : 1x17

A body is found in a pottery store in what's apparently a robbery that was interrupted. Fingerprints at the scene seem to match a twenty year old kidnapping case. Sara and Warrick look into a case where a woman burned to death in her home. The woman was burned to an ash but only the chair she was in was burned, the rest of the house is fine. Sara believes they have a case of spontaneous combustion.