But in no way does it excuse, nor is it sufficient to explain, anything he is as an adult. And increasingly I do not care that he is mentally ill--so was Manson, so was Richard Speck, and so forth. The question is not whether he is mad, it's a question of whether he understands he's doing harm to others or not.
He does, and he enjoys it. So insanity and abuse count for nothing in the face of what he does, and has done.