The taxpayer won't notice the expense. If the Austrians choose to imprison their criminals rather than murder them, then that is their choice: the civilised choice.

If a man is insane, it is inhuman to punish him as if he were sane. I admit we don't know whether he is or not yet, but that is part of his defence and we should not prejudge.

The insane are not simply to be liquidated when they can be looked after. Hitler tried that solution, and nobody thought he had hit on the right idea, did they?