Ben Bennight, the 36-year-old YouTube video blogger from Mississippi, noticed in September an alarming comment on a video he'd posted. He told CNN he immediately contacted the FBI. Bennight told the agents he didn't know anything about the user, he told CNN. ""I think in today's online world, it is very difficult to narrow down who does what without more information," Bennight told CNN's Jake Tapper later Thursday, "and unfortunately, I wasn't able to provide them with much." Update: This story has been updated to reflect new reporting regarding the number of alleged threat reports the FBI received about the shooter.

Source: CNN February 15, 2018 15:16 UTC