I thought OD too, but if he was that drugged up, wouldn’t it have been obvious before he got on the plane? Would they have allowed him to board?
I wonder whether he was flying alone or if someone was with him.
He was with his family and apparently had some kind of pre-existing condition.
He may not have been that drugged up. He may have swallows a balloon full of heroin to smuggle it to Atlanta. If the balloon broke in his stomach (or elsewhere), death would have been pretty fast.