John David Smith III (born 1951) is an American murderer convicted in 2001 of killing his first wife in 1974 and also has been indicted on charges for the 1991 murder of his second wife. Skull fragments found in a locker owned by him belong to a third, unidentified, woman, and a photograph found in his possession of an unidentified woman is the basis of an ongoing "Jane Doe" inquiry.