There are unconfirmed reports it was Paxil, an SSRI drug somewhat similar to eg Prozac.
Illustrates that the law revisions to cover these cases of mental instability have to be done with EXTREME care. The American Medical and Psychiatric Associations have statements and advice out to doctors which seem to suggest that gun ownership is evidence of some sort of mental problem.
How many of us who own guns have been called at various times “gun nuts”? I work in a university and I get that a lot.
It's called "projection". Their abhorrence of anything remotely resembling self sufficiency, or the will power to discern right from wrong, lies at the heart of their own mental disorder.