Totally understand your perspective.  My own knee jerk reaction is to look for areas of commonality for Al Capone (Valentines Day, etc.); Charles Manson (Tate LaBianca); Jim Jones (Guyana); Byran Uyesugi (Xerox shooter); Grace Fortescue (Massie case Murderer); Dylan Klebold and Eric Harris (Columbine); Seung-Hui Cho (Virginia Tech); James Holme (Colorado Theater shooter); Adam Lanza (Sandy Hook); Timothy McVeigh (Oklahoma City bomber); Dylann Roof (NC Church Shooting) and feel the urge to advocate people who share their traits be excluded from the US.  Then, when I force myself to think about it rationally, I conclude that taking action based upon my findings, perceptions, etc. would probably be unconstitutional, or require unconstiutional processes.  One thing I'm sure of, it's a good thing there are limits on what a President can do.  Based on the above list, gun possession/proximity is a completely common  problem.  Do race statistics matter?  Religious orientation?  Org membership?