What is the “preoccupation with themes of violence, hopelessness, despair, pessimism, hatred, isolation, loneliness, or an ‘end-of-the-world’ philosophy” that experts say allegedly drives some people to violence?

The plot, described by one official as being “as serious as it gets,” involved a plan to shoot moviegoers at a Washington State mall as they fled an explosion.

Authorities thwarted a planned mass shooting and bombing at a mall in Kelso, Washington, with the arrest of an Oregon juvenile who had detailed intentions to carry out the attack.