This guy had a history of crime and violence and tried to pull a gun on a cop before he ever enlisted. He’s had problems for a long time. Maybe he’s mentally ill or maybe he just responds the wrong way to tragedy in his life. But I wouldn’t call him a victim or tragic figure.
In the end, we're all responsible for our actions. That's the way I was brought up anyway. Sounds like he used his brother's death to behave badly, and there are always fools who try to make excuses for people like him. Plenty of other people in uniform have suffered devastating losses, but they didn't commit criminal acts as a result.