Whatever happened to due process?
Just short-circuit everything and go straight to confiscation, for your own good, of course.
I have posted this before, but the same recommendations could be applied to FINDING the potential mass killers BEFORE they have become a very difficult sociopath. This would not apply immediately, but looking at the long term, many serious confrontations could be either blunted or avoided entirely.
Acquaint ALL children of school age with the reality of firearms. Starting in the primary grades, instructions on how to AVOID being accidentally shot by an unsecured handgun they may happen upon. Also, allow the RETURN of fingerbang and toy guns, cap pistols and air rifles to the access of those in the early years of school, so guns do not retain an air of mystery that may be totally fascinating to the young mind. This also gives insight to the kinds of interactions that point to the predispositions of the youth as individuals. With the acceptance of these devices, it is also necessary to make sure the children have also been fully informed of the responsibilities of safe use and proper care of these devices, and rules of conduct while handling them, even in play. The idea here is to identify at a much earlier age those children who may either be totally afraid of the very idea of hand weapons, or so brazen that they far too quickly adopt the idea of using this kind of device in bullying tactics, which they would quickly reveal. The eternally timid should be given further instruction in means of avoidance, evasion, or how to escape once in a highly vulnerable situation. Also tattoo their Social Security number and name on some part of their anatomy, so the remains may be quickly identified, should they be so unfortunate. For the brazen bullies that WILL cause trouble later in life, counseling and/or psychiatric intervention at this stage may be a way to forecast or forestall future need for intervention, when the situation is much more serious.
For the remainder of the more normally-orientated children in middle school, familiarity with all types of side arms is much encouraged, with even some target practice with light-caliber sidearms, and by the time they are in high school, competitive range firing with specified skill levels as part of the school curriculum.
Guns become totally demystified, being a thing in which youth is in full contact with, and all the rules of care, feeding, grooming and proper use and storage have been instilled in the responsible youth, while identifying at a much earlier age those of whom should NEVER come into contact with weaponry of any kind.
Like I said, long-term, to first overcome the prejudices, and to make sure the NEXT generation is adequately prepared to be available for military training and careers in law enforcement, as well as common home defense. And to weed out the bad actors long before they may develop into a threat.
Of course, there would be some who would want to blow this proposal up into something sinister immediately, and I can only say, superstition is a dreadful taskmaster.