The nutcases.
The only real nutcases are those who believe that Oswald acted alone and that his murder in turn by a fellow with deep Mafia connections while Oswald was in jail was the work of a man who was feeling sorry for Jackie and the kids.
And that Ruby died of a brain tumor of natural origins.
Those are the nutcases.
There are too many unsavory characters hanging around the periphery, too many past associations among the web and too little motivation from Oswald. He was a patsy, set up to take much of the blame.
And it's too embarrassing for the various agencies to release the truth.
Arf