First degree murder is the most serious level. It would be things that are premeditated or intentional.
There was a case here a while back where a law enforcement official shot and killed his wife. He said she attacked him with a knife. He wasn’t injured, I think there may have been a scratch on him.
He did unload his gun on her but that would have been his training kicking in. He was obviously arrested and charged but as the investigation went on (he did lose his job), there was enough evidence found regarding her behavior and events leading up to the incident to dismiss the charges. (change them - I don’t remember if it was involuntary manslaughter or what it ended up being - but no jail time) I saw him coaching a rec basketball game not too long ago.
So these charges against Barisone may stick but since we don’t know exactly what happened they could end up being dropped or lessened, especially if they decide he did not show up there planning to shoot her. That “I had a good life” statement was odd and sounds like he knew he screwed up.
As for the gun - that will be interesting to find out if he brought it with him, took it from her, took it from the boyfriend etc. If the boyfriend is as shady as people on social media claim, it would be interesting to find out that he was actually outside when all this went down… (I’m not saying he was - just thinking this is definitely going to be an episode of Snapped when it is all said and done).