How about, while turning around from trunk of car and holding shotgun, stumbles, trips over his own foot while turning around, as he is falling, lets go of shotgun and reaches for the ground with hand to aid in fall , shotgun flips around in mid air, and as he is still reaching for the ground finger goes into trigger guard and force is applied to the trigger, all while a round is chambered and safety is off. How else could this happen? Sometimes when your around guns a lot, you forget that they are dangerous, if you do not follow the rules, so you end up not following the rules , one rule at a time, then it is only a matter of circumstance and fate before something goes wrong. Remember, always follow the rules of safe gun handling.
or could the possibility be that it was self inflicted. I was not there , so I do not know. Sorry of what has happened here. We were all very surprised about Millis. but the thought did cross my mind then, just being polite.