Post Civil War glitch.

I've been playing a character that is not allowed to get anything in the crime stats section, except for lock picking and trespass counts that are unavoidable. I've finished the civil war, siding with the Imperials, and have come across a couple of Stormcloak camps I've wanted to take out. It took me a while to work out how to get them attacking me (I've previously either just gone ham or used mayhem) but was both surprised and frustrated to find a murder count in my stats at the conclusion of the fight. I tried a few times and made certain everyone was attacking me before I killed them, but each time there is still that one murder count. Even taking out the soldiers in the first aid tent didn't generate so much as an assault charge, despite not being aggroed on me, but somehow killing someone attacking me counts as murder? Can someone please explain how this makes sense, or even better, a way around it, even if it means using mods?