After several years of research, studies have found that the behaviour of raping kids, killing dozen of womans, etc is not caused by social context. It can be triggered by the social context, but it's unlikely to be created under bad social context.
I've read some words from some psychiatrist who said that it's impossible to change the mind of those who are diagnosed as phychopaths, they won't respond to any attempt made to change their minds. Unless you can trigger some biochemical reaction in their brains, better lock them in prision forever.