Omar Mateen, the Orlando gunman who killed 49 people last week, had run-ins at school, workplaces, gyms, even in online dating.
A "New York Times" profile published over the weekend found numerous instances of acquaintances and co-workers who say Mateen was "always agitated" and "always mad." Many large workplaces and schools include people who are antisocial or prone to anger.
How can you tell if those traits are dangerous? And what can be done about it?
Casey Jordan, Ph.D., Criminologist and Professor at Western Connecticut State University