I remember the snowmobile shooting. .35 remington, I believe.
I know that younger people do it all the time. a 16 year old in that same city shot his girlfriend in the head, in her own bedroom, because she broke up with him. his defense was that he brought the gun to kill himself, had it against his temple, and she yanked it out of his hand, accidentally shooting herself in the head (complete with contact burns) Do you remember the kid in arkansas that took his father's 742 30-06 to shool and sniped the elementary school playground? Can't very well plead that as an accident, can he? (good evidence that the recoil of a 30-06 is tolerable)
prosecuting tragedy doesn't do any good.
prosecute malice, then put them in stocks in the village square so that the peasants can throw horse fewmets at them. When the peasants get bored, give them a proper hanging. I think that we both probably mostly agree here, at least it seems that way.
They did decline to prosecute because there was absolutely no evidence of preplanning, malice, or motive.