Given the evidence and after John Ringo's account (along with years of dealing with my own mother while she was on it), I'm going to have to go with the Diazepam turned a highly organized, perhaps high functioning semi-autistic type, into a murderer.
I know how mean and vicious my mother was during the ten years she was on it. I could easily see it turning someone who had just recently started taking it into a mass murderer. Nothing else explains it. (Despite what the conspiracy theory nuts think.) He doesn't seem to have a motive, other than "Kill lots of people". Not ISIS, not Anti-Trump, not "Hates Country Music", or even "Hates music". There was simply nothing (or at least what anyone could find) or ANYTHING that would give a hint as to the "Why?".
Yet, he shares with many other mass murderers, the same use of psychotropic drugs, in this case he had started to use them not long, like a month or two prior.
Unless they can come up with something, anything, that might point to a motive, that's the only explanation that fits.
