Whether it's guns or mental health as the core issue, this country is not going to police everyone to the extent that would be required to make sure it NEVER can happen again. Because that's not possible. Many of the killers aren't in any serious legal problems until they kill.
How much "intrusive government" would there be on limiting at least certain guns/weapons versus checking out each and every American to see if they have killer tendencies. Or are depressed. Or whatever. I'm fairly sure one could claim that most Americans would qualify as depressed at least one week each year--we live in stressful times where there's not a general sense of community. Sometimes it's hard just to get through the day and everyone is usually locked into their own survival; not physical survival, but emotional survival--which is what seems to be the big trigger.
I have no idea what to do, but ideas need to be brought up, discussed, discarded/attempted, etc.