Mary was last seen in Morgan City, Louisiana on March 2, 1978. She went to the pharmacy on Victor II Boulevard and never returned home. Someone later called her parents to demand a $5,000 ransom, and Mary got on the phone to tell them she was unharmed. This is the last time anyone heard from her, and the ransom caller never provided any instructions about where to deliver the money. Her car was found abandoned in the pharmacy parking lot. Authorities believe Mary was a victim of the serial killer Robert Carl Hohenberger, a former sheriff's deputy from California.