This article categorizes nine perpetrators of rampage attacks as psychopathic, psychotic, or traumatized school shooters. The shooters are Eric Houston, Gary Scott Pennington, Jamie Rouse, Jason Hoffman, Robert Steinhäuser, Alvaro Castillo, Eric Hainstock, Tim Kretschmer, and Wellington de Oliveira.
This court report reviews Houston's early life, his preparation for the attack, and his actions during the attack, including the hours during which he held people hostage. Much of the document deals with Houston's appeals and why they were denied. This is the best source of information on him that I have found.