psycho killer

Whenever I read or hear about people who do terrible things to other people I always wonder why. What's wrong with people that they would want to cause pain to another living being? This morning I happened upon this interesting article in Scientific American which sheds some light on the subject. http://www.scientificamerican.com/blog/post.cfm?id=the-problem-with-psychopaths-a-fear-2009-09-29

Of course, it doesn't completely explain why, but it's another clue in the puzzle. I think it would be interesting to work in the field, ie, abnormal psychology, but also unsettling.