The thing that gets me is that he had that AR-15 with (at least) two fully loaded clips of 15 rounds each in his truck. I can see him carrying his service pistol around with him, but an assault rifle? Either that was normal with him(in which case it says something about his mental state) or he packed that weapon with him that night for a reason. And that smacks of premeditation, not a crime of passion by someone who just ‘snapped.’
You have to wonder if there wasn’t something evil in that SWAT training that he had just received....