I agree with you about prison not being a panacea for criminal / violent behavior.

When given the chance to address the court prior to his sentencing, DePape, dressed in prison orange and with his brown hair in a ponytail, spoke at length about Sept. 11 being an inside job, his ex-wife being replaced by a body double, and his government-provided attorneys conspiring against him.

“I’m a psychic,” DePape told the court, reading from sheets of paper. “The more I meditate, the more psychic I get.”

While I don't think that DePape should be released into the public, it sounds like some sort of psychiatric facility would be more appropriate for him. Ignoring mental health issues is not going to make them go away and maybe if he and others like him were put someplace where he could be observed then we, as a society, may be able to put some policies in place to address future potential dangers before they culminate in violence.