Trying to make sense of it all

By now, just about everyone has added their comments to the web about what happened here in Aurora early Friday morning, but I feel I need to comment on it as well.
Colorado has seen it's share of tragedies, with school shootings and fires, but this one is so much more intense for us.  Part of it, I'm sure, is because Rebecca and I are both a lot more emotional about crimes committed with guns after she had one pulled on her earlier this year, but it's more than that.  This horrible tragedy happened at our theater.  Rebecca and I had our first date at this theater, and we've seen a lot of movies there...possibly even in the theater where this happened.  When I stand on our balcony and look up the hillside, I can see the sign for this theater.  This was almost literally in our backyard.
I majored in psychology in college, but I can't even begin to fathom what was going on in this guy's mind to think this was the "right" thing to do.  Understanding criminal insanity is often hard, but as a writer, I've learned to put myself into a criminal's mind and try to come up with reasons for why they do the things they do, but I'm stumped on this one.  I really just don't understand.
Worst of all, before bed last night, our seven year old started crying, saying that she was worried that someone was going to come in and kill us during the night.
This guy has hurt so many people, and I'm certainly hoping there will be justice.