Preventing Violence: A Closer Look at How to Predict Triggers

Forensic psychologist Dr. Stephen Diamond says many of the people committing the mass killings we have seen in the past few decades, like Christopher Dorner and Adam Lanza, have been void of the usual triggers of violence. This is making predicting future violence harder than ever. Lolita Lopez reports for the NBC4 News at 5 p.m. on Feb. 21, 2013.