And what now? Are we to allow these people to spill their misery into society?
If they are broken in the head - fix them. If we can't fix them - isolate them. Can't isolate them - kill them.
Sory - c 'est la vie.

I myself am a determinist and i think each one of us (as well as our every action) is a product of unbroken chain of events and couldn't have gone any other way. However i don't think this can be used as an excuse for people like those. If anything, you can't blame society for finding them repulsive and hazardous, can you?