The wife's story as well as hunter's son mistaking the sound of the gun shot for a book falling suggests foul play. You can't rule that out over some unsubstantiated drug shit.

Did the wife say hunter sounded like he was drugs? Did the write from the toronto newspaper who spoke to hunter the night before say anything to suggest hunter was under the influence of drugs? did hunter's son who was in the house during the shooting say anything suggesting that his father was acting like he was on drugs before the shooting?