“Previously, school shootings were a model for people who were lonely, isolated and suicidal. The warning signs that often precede such attacks haven’t changed even as school shootings and online extremism have merged, they said. The Evergreen shooter’s online footprint showed he was exposed to violent content in the dark corners of the internet. Federal law enforcement authorities have now named the phenomenon, but the rejection of society has always been at play to an extent in school shootings, dating back to the 1999 Columbine High School attack, he said. Kids don’t have to seek out violent content for it to show up on their social media feeds unprompted, Hawks said.