I am doubtful that he can, or even should, be just locked up forever -- unless, of course, in the time that he is in prison he shows no signs of having changed. What I really mean is that I'd hope that he can be rehabilitated, as ought to be the primary purpose of prison time.
From what little I've seen of this, he doesn't strike me as what I'd usually call a "savage". I'm not quite sure of what else I'd label him -- I'm worried that I'll slip into the "society is to blame" line and I don't mean that at all! Maybe "pathetic"? I mean, have a look at his handwritten note at the bottom of your link. The content aside, it looks like it was written by a primary school kid.
A failed education? Angry, lonely young man? He needs help. Help, I hasten to add, that should be provided while he is behind bars and no danger to the rest of us, but help, all the same.