It's actually interesting and totally understandable. When we lose someone so close we have immense emotional response. This poor man just wasn't strong enough to deal with his effectively and was overcome with hate. As we all know, hate destroys only the one who harbors it.
He had done good in the community, he was just over welded by his loss and the heroin epidemic. Wanted to avenge his daughters death.
It might have been many of us on a bad day. I feel bad that the guy didn't get the help he needed to let her go. Sad story for sure. Heroin and meth are destroying so much, I'm not far off from blasting a few dealers myself, if I wouldn't lose everything cause of it.