TRENTON, S.C. (AP) — Investigators say a 60-year-old man who strangled his girlfriend died of a heart attack while burying her body in their South Carolina backyard.

Edgefield County deputies say authorities found Joseph Anthony McKinnon’s body Saturday after neighbors called and reported an unconscious man in a yard in Trenton. Authorities say as deputies investigated McKinnon’s death, they found a body wrapped in trash bags in a freshly dug hole and determined it was his girlfriend, 65-year-old Patricia Ruth Dent.

An autopsy on Dent determined she had been strangled and neighbors told officers they saw McKinnon digging a hole in his yard the day before.