The Key (S04E07)

The 1979 murder of a schoolteacher who was stabbed to death in a wooded area is reopened when the victim's bloodstained jacket is found stuffed in a tree trunk with a happy-face key chain in a pocket. The case was originally investigated by Jeffries when he was a rookie detective. The probe reveals the victim died two months after attending a key party she left with a neighbor, a man with whom she had an affair. (CBS TV Network)