Okay, I can talk.

Tricia said so.
My mother knew Timothy. I can't recall how, I don't think it was school, but may have been college, she studied all over the country.
From what I remember and what she has said, he was never outwardly angry or very expressive at all. (Now, I don't know how he was behind closed doors.) He did have empathy, though. If you could find the underdog, you could find him, just look in their corner. Not really the kind to get out there and shout about it, but quietly encourage those he felt were in the right.
I can't say what motive was, if he was suing them for a lost pension though, I can see that messing with his head. (As it would anyone.) But as far as why he would open fire on people that he worked with, I have no idea.
But I wouldn't be surprised to know that he just felt there was nothing to fight for, but the need to lash out anyway. My mom has said that he was the kind that really thought people should work all their lives, if capable, and then get to relax in the golden years. He may have set this goal for himself, seen his retirement in his head, and then had it and his security net taken away. Not excusing, just speculating. Nothing excuses this type of action, this kind of tragedy.
My mom was not really close with him either, but I read a letter he sent a few years ago, and I do recall meeting him, although I can't tell you precisely when, without digging out pictures and stuff for reference.
Mainly I would just ask about the people in her photo albums and she would tell me, so it's not like he was a household name, but I do think, from the little bit that I knew, that there will be a lot of shocked people, at least on the outside. I don't know how those close to him would feel.