Maybe they could float a reality tv show of him at Pelican Island sharing a cell with a couple of two hundred eighty pound gang members who hate baby killers. ( ..." NO BUHBUH PLEEEEEEEASE, NOT THE SHOVEL HANDLE AGAIN!) Bring back pillorying on the town square.
If things are handled properly, a person sentenced to a mental hospital can remain there longer than a conventional prison sentence. I doubt this would apply in his case though. He could be confined/treated till sane then tried.
Look at that face, its just begging for a baseball bat across it. Little girls like the one he killed are sacred. Vile fiend.