How can we better identify potential mass shooters while respecting civil liberties?

So the Texas shooter had several social media posts indicating he was a sociopathic wierdo. His classmates felt uneasy around him.

Shouldn’t we figure out a way to flag these guys and at least temporarily prevent them from purchasing weapons?

I don’t believe in restrictions on gun types, magazines, etc. But I don’t mind something like a mental health screening or questionare before buying a firearm.

Something that if you are not ok you have to go get cleared or wait 30 days before purchasing.

Requiring FFL holders to undergo training to detect signs of mental distress, suicidal ideation, etc. And then give them tools to refer people to counseling if there is an issue.

These are some ideas but the point is we can’t just let this situation go on because overtime I believe the ones who want to curtail liberty will win.