On January 5, 2018, a person close to Nikolas Cruz contacted the FBI’s Public Access Line (PAL) tipline to report concerns about him. The caller provided information about Cruz’s gun ownership, desire to kill people, erratic behavior, and disturbing social media posts, as well as the potential of him conducting a school shooting.
Under established protocols, the information provided by the caller should have been assessed as a potential threat to life. The information then should have been forwarded to the FBI Miami Field Office, where appropriate investigative steps would have been taken.
Find it surprising that the FBI was given some indication, and they didn't investigate it. Or perhaps they didn't look into it closely at all, it's possible too that the caller was not credible.
This happened to me once on a website. Just as I was signing out, someone threatened to shoot up a university in a US state. The message was deleted soon after, by the site, but not before I took a screenshot.
I reposted it, by the time it was up, within two hours several people in that state and at that university were informing police, students were leaving the campus. I couldn't have ignored it, or taken the chance that it wasn't real with people's lives at stake.
Three hours in, police were at the home of the person who made the threat. It was a fake, put up by a teen. His parents were horrified, embarrassed. Local police acted so quickly, that it was over by midnight.
When this kind of threat (or information about someone who is dangerous) is given, police locally should be informed as they are on the spot, may know the family. It seems like the FBI, is too large and they must get this kind of information regularly, it might be difficult to sift through the real and the fake.