Schizophrenia is of a genetic predisposition combined with environmental exposures and / or stresses. While James was in Riverside, he was an hour and half from home. Now James is in Colorado, and more alone than he's been before. That is a big stressor. How many hours is he putting into study at school? Anxiety/stress/isolation may have been the first symptoms and could/heighten over time. They say James had friends, but what was the quality of those relationships? We don't know at what point he began seeing Dr. Fenton. Was James seeing her for anxiety/depression/stress or had other symptoms more serious already begun? He would've been going for talk therapy, but he would also (most likely) have been prescribed medications. There are whole ranges of prescription medication for mental illness that may have been prescribed. If James had had some of the more serious symptoms he may have been prescribed at that point an anti- psychotic. Some of these medications can wreak havoc on mental capabilities creating more stress for him as his success with school work declined.
I watched the YouTube video someone posted above about the woman with paranoid schizophrenia. A section from that show came from NPR and tried to express what it would be like for someone with schizophrenia. If that depiction of someone with schizophrenia, doing simple chores , and having voices giving you different orders at different times in relation to different things is typical of schizophrenia it really wouldn't take much of a leap to see James Holmes carry out the crime that he committed under whatever delusions he had in those circumstances. But, those crimes would have been committed by the delusions and paranoia.
Everyone wants a motive; everyone wants something to point their hatred anguish and grief at. If there was something that could be understood things might be a little better. If it is schizophrenia then that is where the hatred and anguish should be aimed. It's like a tornado that moved through with heavy destruction. The tornado is gone, and leaves tragedy, grief and loss in its wake. Everyone hopes that more will be learned about tornadoes and that it will not happen to others.
There is evil in this crime/tragedy and I believe the evil is mental illness.