An autopsy today could shed more light into the death of a 56-year-old man — found with an apparent gunshot wound to the head inside his northern Butler County home, authorities said.

State police labeled the death "suspicious," but they have not determined how or why — by homicide or suicide — Clifford Stevenson died.

He could have been dead for up to two days when a family member found his body about 6:30 p.m. Thursday, police said.

Also a mystery is what happened to Stevenson's roommate — 49-year-old Thomas Smith — who had been living with Stevenson at the same house on Route 8.

Police reported Smith as a missing person. He is not considered a suspect, but investigators want to speak him.

Smith's family members told investigators they are concerned for his safety since he had not been seen since Tuesday.