There should be a resource officer in the school. I've known some who are really good. Retired LE. A person like that sitting in the parent conference can size up the threat better than school admins, and can call in to local LE for background checks, if needed.
The school's problem will be if the rumors that surfaced on the day of the shooting that some kids told their parent's that there was a credible shooting threat and they were staying home prove to be true That, along with rumored pictures of a weapon on social media posted by Crumbley in advance of the shooting. If true it had to be circulating in town and some staff would have known through the grapevine. They would let the SRO know,
Was in a situation once that was similar. Credible threat. Pictures. Suspect was a psycho. There was a major school event that took place shortly after in an area, adjacent to an area I was responsible for. Curtains were drawn that were never usually drawn so I went up to see if kids snuck in and were fucking around. It was Staties with rifles sitting at seams in the curtains, Rifles at the shoulder.
Kid had been removed from the school, but LE wasn't going to leave any stone unturned.
That's why I think the sheriff speaking up means something. He should have known from the rumor stage. If the school resource officer was on duty and not in that meeting the school is in deep shit.