There had to be layers of "in the know." The innermost ring of personnel knew it was an entirely staged event. All the remaining "rings" had no reason to believe it wasn't, based what information they had available to them. Potential loose ends from law enforcement, people who could potentially blow the cover, would be bound by very austere nondisclosure agreements from the Fed/state (i.e., job termination and "no juicy-deal pension for you, pal" -- or something worse). As a local, I can tell you that nobody knows anything more than anyone else about what happened that day, aside from the emotional currency and leverage that comes with being geographically near the "crime." The Newtown people know precisely as much about what happened as people watching on their TVs in, say, Melbourne, Australia. The event was a closed set. Info/disinfo that came out to the media was strictly controlled. Everything that followed was just reality show biz.

Any group of 10 or so reasonably intelligent people with a very big budget, access to state/federal resources, and years of planning could easily assemble the logistics to prepare a movie set, coordinate events, and carry out an event packaged and sold to the world as a tragedy. A big part of this operation would be the disinformation team, who would create sub-stories that all lead down rabbit holes. Algorithm creators.

Denying people their FOIA rights, censoring, internet harassment, and ridiculing people asking too many questions -- the PR clean-up crew of this operation -- is a project a bit less clear to me. Their work continues but will probably shut down in due time. That seems a bit messier to handle.