Drugged. Although I doubt if the cops care to drug-test a dead guy like this. I would take a guess if you drug-tested active shooter episodes....a large majority would have something in their system. No one wants to open that door.
Might get a meme going... if you want a good time (at least on earth) going out shooting, take X-adol.
Might just be hashish as in the assassins of old.