The stab wound was in the back of the bears head. Normally when a bear is fighting it will turn its head towards the attacker and it is not possible for this at

The stab wound was in the back of the bears head. Normally when a bear is fighting it will turn its head towards the attacker and it is not possible for this attacker to stab it in the back of its head. So this was probably either a lucky hunter who discovered a hibernating bear or a member of a larger group of hunters that was able to sneak behind the bear while other members kept it occupied.