Aaron Alexis has been identified as the man who shot and killed 12 people at the Navy yard in Washington, DC. His motive is still unknown, and he’s dead so they can’t ask him why he committed such a heinous crime. But it could have been prevented, perhaps, if he didn’t have a security clearance. He had been arrested at least twice for illegally discharging a firearm. He had a history of playing violent video games and he was being treated by the Navy for mental health issues. So can anyone explain why he was given a security clearance?