JFK and the Unspeakable

I am currently listening to this talk about the assassination. I am currently reading David Talbot's book Brothers and will try to read this Jim Douglass book. He tries to link the JFK, RFK, Malcolm X and MLK assassinations. All of the following are Douglass' claims, I am noting them to look into later.

Secret service men block grassy knoll? Look into.

Joe Marshall -- smelled gunpowder behind fence. Man showed him he was a secret service agent.

Ed Hoffman also saw phony secret service men. Lacked hearing -- but saw what happened. Walked, could look down from the freeway. Could see railroad bridge. Absorbed with two men behind fence in grassy knoll. Suit man -- railroad man. Men working together? Saw puff of smoke from the suit man -- firing of the rifle. Tossed rifle to railroad man, who ran north toward tracks. Suit man confronted by police. Hoffman ran to his car -- visited FBI and police, who ignored him. Was threatened by the FBI? Hard to evaluate, since those who deny that he gave coherent testimony are those who would lose if what he said is true.