Before the shootings at Sandy Hook and Isla Vista, there was Virginia Tech, where a young male purchased two handguns several weeks after he was adjudicated to be a person who was a danger to himself and others. Both pro- and anti-gun groups had been lobbying to have those adjudications computer linked to the felony database without success. Felons, by law, cannot possess firearms.
All of these young male shooters had exhibited very bizarre behaviors; some were in mental treatment well before these tragedies occurred.
If all of the groups who wish to stop these tragedies were to band together with experts such as psychiatrists, constitutional experts, behaviorists, computer experts, law enforcement and legislators to construct a workable, legal definition of a person who should not be in possession of a firearm by reason of mental defect, and then place that person in a database connected to the felony database, many of these tragedies could be avoided in the future.