I've had any number of times that Snowy Granius on the bridge to Arkngthand attacks me first, and the guards penalize me for his death when I defend myself. I've even tried luring him to the Fort without attcking him, and the guards still do nothing other than fining me when I defend myself and kill him. The penalty gets placed even if all the action takes place on the bridge itself. I've noticed similar behavior happen in the game in some other spots too, such as when clearing out a bandit lair, and there's no one around as far as I can tell.
Can someone explain what's going on? It certainly messes up the game when it happens to the point that I save the game before crossing the bridge and meeting him. UESP has no info about the game's behavior re: Snowy.