In the months leading up to his 2012 attack that killed 26 people in Newtown, Connecticut, a 20-year-old man exhibited a cascade of concerning behaviors. He experienced worsening anorexia, depression and obsessive-compulsive disorder. His relationships deteriorated, and he became fixated on mass murders.
In 2013, an 18-year-old had enraged outbursts at school and threatened to kill his debate coach. Concerned, the school’s threat assessment team interviewed him, rating him as a low-level risk for violence. But three months after the assessment, he shot and killed a classmate and himself on school grounds in Centennial, Colorado.
