How many of them had prior mental problems and were treated for it? It's my understanding that a background check does not include information on mental disorder. THAT information needs to be included in a background check.
No. You want a person found too incompetent to own a firearm? Has to go to court.
We've already seen libs move to take vet's rights away for life by claiming PTSD, we've seen them try to take Social Security recipients' rights away as being incompetent because they have their check mailed to somebody else, libs have made moves to have people declared permanently incompetent for grieving after the loss of a loved one, we have states trying to pass laws allowing a "near relative" or police officer to declare you are a danger and automatically take 2A rights away without due process (I mean, nobody has ever had an evil ex, right?).
No more. Psychologist and court and the right for a wrongly accused person to sue for violation of rights.