The month before she vanished, her boyfriend Roger Allen and his father, Clarence, robbed a grocery store, Fran’s Market. Mary helped Roger cash some of the stolen money orders ($10,000 worth!), and then told the store owners’ son, Bryon Schletewitz, about the robbery.

Clarence Allen was extremely angry when he learned what Mary had done. He ordered her killed. Another man, Lee Furrow, strangled Mary, then weighted her body and threw it into a canal. Her body has never been found.

In 1977, Clarence Allen was convicted of robbing the store and murdering Mary and sent to prison. Furrow pleaded guilty to a lesser charge. But Clarence didn’t stop there. To silence witnesses who testified against him, he ordered the murders of eight people, including Bryon Schletewitz and his father. In 1980, two hitmen killed Schletewitz and two teenagers working at the store. A fourth person survived the shooting. The hitmen were caught before they could kill anyone else.

Clarence Allen was later convicted of three murders and sentenced to death. He was executed in 2006. His son Kenneth, who helped the hitmen, was given life in prison.

Because of Clarence Allen’s actions, it’s believed Mary’s disappearance was a murder, even though her body was never found.