It's obvious a guy like this will never be able to live among other people again, so he should be imprisioned for life (not that it is possible in most social democracies, still...), but why bother sustaining him for maybe over 50 years with people's taxes money. Kill him and broadcast it if you like. Wallets and hearts and human rights supporters will likely be happy alike.
Of course, if you want to go all out and cast away any, mmm, moral constraints, you can bathe him in molten lead, saw him from genitals to head, drip water in his shaved head for a year straight and so on. Wicked and uncivilized, yes, but maybe it's even the better choice, considering his acts could inspire others if his punishment is relatively brand.
But who knows, when a man already shows to feel nothing at all, what is pain to him? In the end, the worst it could be done to him is rebuild everything he tried to destroy, forget about him and live life as if nothing changed to show him his twisted logic is worth naught.
