What sort of breaks this approach though is the recipient of that document. It's not a simple report or something that would just go into the "X-Files"...

While I don't know enough to say it for sure "Director, FBI" sounds like some serious business even if it's not THE director (which is the way it sounds to me right now though). I don't think someone would make up an extra letter just to tell some gossip & rumors or crazy talk. I'd think something like that would just go into a file (if at all) and wouldn't be sent around as seperate letter...