In 1981, New York correctional officer Donna Payant disappeared and was later found in a landfill. The medical examiner not only identified the cause of death, but also found an important clue. It was a signature element of a murder committed by Lemuel Smith 10 years earlier, which was also investigated by the medical examiner. Upon further investigation, it was discovered that Smith was an inmate at the same prison and could have committed the crime. But, did he?