Would Death by a thousand cuts work?
http://www.answers.com/topic/death-by-a-thousand-cuts
I say kill him, don't care how, but in the future if your gonna let one out you gotta first: pour acid on their face and blind them, castrate them, cut off their hands, remove one kneecap, install a taser system to go off every ten minutes and tattoo 'child molester' on their head.