Ivan Lopez, the Army Specialist responsible for the deadly Fort Hood shooting on Apr. 2, was undergoing treatment for mental health issues but had not been diagnosed with PTSD, according to military officials at the post. While he had served in Iraq, Lopez had not seen combat. So, did PTSD play a role in the shooting spree? NBC 7’s Bridget Naso speaks with Dr. Kathleen Kim, a psychiatrist at the VA in San Diego who says research shows the best predictors for violence is previous behavior and not a diagnosis of PTSD.