The new material included at least 10 police body camera videos and nearly 40 dashboard videos that largely affirm prior reporting by ProPublica, The Texas Tribune and FRONTLINE detailing law enforcement’s failures to engage the teen shooter who killed 19 children and two teachers. Officers only confronted the gunman 77 minutes after he began firing, a delay that U.S. Attorney General Merrick Garland said cost lives.

Police Chief Homer Delgado ordered an audit of the department’s servers, which revealed even more videos had not been turned over. He shared those with District Attorney Christina Mitchell, who is overseeing a criminal investigation into the botched response, and ordered his own internal probe into how the lapse occurred.