Police discovered Mary Whetsell's body Saturday, the Pittsburgh Post-Gazette reported. She died four years ago.
Kenneth Zang's action came to light after Whetsell's estranged son, Howard, came to the house in Turtle Creek last week. Zang told him his mother was dead and buried in a cemetery, but Howard Whetsell went to police when he could not locate his mother's grave.
Zang told The Post-Gazette he buried Whetsell in the yard because he did not have the money for a proper funeral and because she had told him she did not want her son to know where she was buried.
He faces charges of abuse of a corpse and Social Security fraud.
"I did wrong, and now I've got to pay for it," he said.
Zang, now 58, said that he met Whetsell in 1982 when her son bought a car from him.
He said that after mother and son became estranged, he helped her, and they eventually moved into the same house to save expense.


