The Philadelphia Medical Examiner's Office tells us Giganti's body tested positive for drugs from a standard urine drug screen. The office wouldn't say which drug or drugs were found in the chef's body.

Law enforcement sources tell us cops got a call Thursday from a neighbor for a foul odor. When cops showed up, they found the door wide open and his body sprawled on the floor of his bedroom.

Giganti -- who famously feuded with Gordon Ramsay in season 16 -- was 36.