Honestly, I do think that letting people get away with these sorts of things is very dangerous. This is, in fact, something I argued on another site with someone else:
(NOTE: this was regarding the creature/Cheyenne Cherry who threw a kitten in an oven as a "joke" but could apply to this as well):
Just imagine having something like her living in your building. Think about your cats, or your friend's/neighbor's cats. I lost three of my greatest friends all last year, and their deaths changed my life forever. I have more companions now, one that I view almost as a son. And the thought of one of them being thrown into an oven and tortured to death...it makes me physically ill. This story, right here, happened in a different state, but if it had happened to me, I don't know what I would have done. I probably would have killed her.
Now, imagine her being set free again. Imagine the kinds of things she will do in the future because people were too naive, too soft to put a stop to her evil. Think about the innocent animals/people that she is going to torture. The blood of those innocent animals/people will be on the hands of those who did not act out, who did not take a stand despite having the power and the opportunity to do so.
As for curing the guy who killed the cats in this article, or the girl who baked the kitten...honestly, at this point, there is no cure. If it's come this far, there's no hope for people like this. They aren't even people anymore. They're just monsters. Either lock them away or kill them. Just don't give them the chance to hurt more innocents.
Volke: You there, in the bushes. You have until the count of five to show yourself before I start throwing sharp objects. One... two... four...