Mass killings have become so commonplace that they've become part of the background narrative in the news.
The Alpha Group Center has a course that's designed to identify killers before they go on a rampage. Mike Roche, the instructor for the course, is a retired Secret Service agent who who's actually written a book on the topic.
Mass Killers by Mike Roche
You can find out more about Mike, the Alpha Group Center and the training course, Mass Killers at http://www.alphagroupcenter.com