Bingo. There was a video analysis post on this I posted a few hours ago eluding to this. The guy off to the left about 30ft or so away shot his pistol first, before Kyle fired. That may have been the shot that killed head wound guy. There was no exit wound that I could see, indicating a bullet of less impact than Kyle's rifle which would have blown the side of his head off. This is good, the bullet should still be in the skull, could be proven not to have come from Kyle's rifle.