He did tell us a few of the things: he got called names, he thinks his peers are government controlled, and that the way to get power over his life is to shoot them.  He's clearly delusional, but he was absolutely right about the enemedia making him famous.

It's damn sad no one reined this kid in.  It's not like they didn't have chances to do so.  Not only did they leave him on the streets, but it seems pretty likely from his resentments that some folks and perhaps his meds wound him up instead of calming him down.  Almost seems like he was aimed at that school like a weapon.