It is already against the law for the mentally incompetent to buy a firearm. The only new law that might help is to make it easier to adjudicate people mentally incompetent. That’s a new mental health law not a new gun law. Is that what you’re proposing 0bummer?
Not long after the shooting happened, I remember reading that it is easier to get someone involuntarily committed in Arizona than in most states. If that is true, then the young man involved should have been evaluated before the shooting and before he bought his gun.
Not only had he had previous legal difficulties, which were glossed over and not used to mandate a mental health evaluation; he was expelled from the local community college with the explicit instructions that he not return until he could present evidence that he was not a danger to himself nor others.
That certainly should have triggered an involuntary commitment action.
The failure here was not a failure in the gun purchasing system; there was nothing in the system to set off an alarm. The failure was not in the mental health system, which can't help people it does not know. It was not a failure of the educational system; the college can't seek a commitment.
If the legal system- the local sheriff's office- had pressed for an evaluation when it first became obvious that there was a problem, then perhaps the young man could have been helped and the whole episode averted.