Pittsburgh PA – Police are investigating the death of a 78-year-old man at a North Side high rise Thursday.

Tonya Norris said she discovered a strong odor of gas when she arrived at her uncle’s Pressley Street apartment.

“The stove was on and the oven was on. He was slumped over in a chair. I felt his pulse and didn’t have a response,” said Norris.

Norris said her uncle — James Harrison — suffered from dementia.

Harrison may have turned on the oven and burners while trying to get warm.

Police suspect carbon monoxide poisoning as the cause of Harrison’s death.

An autopsy has been scheduled for Tuesday