Why did Eric Harris and Dylan Klebold murder a dozen students and one teacher—and then kill themselves—at Columbine High School? In this A&E Special, the renowned Threat Assessment Group comes to Littleton, Colorado, to perform a psychiatric autopsy to better understand why Harris and Klebold killed. Armed with that information, TAG hopes to educate parents, teachers, and students on how to see the warning signs of impending violence and intervene appropriately to stop such tragedies before they take place somewhere else..