This incident gives a lot of folks reasons to spout off about supposed ills in our society.
Parents, or no parents...this guy should have been locked up. The school, the police, the sheriff, and the FBI failed.
Liberalism demands that the mentally ill (or bad criminals, too) be given every chance plus some. By all means, don't confine the little dears.
There was way more evidence than needed, to lock him up. That is the first thing to do.
Next one can wonder if he is mentally ill, just evil, or both. Either way keep him locked up.