And this month, on the eve of the report’s 50th anniversary, the roster of seemingly credible Americans willing to identify themselves as Kennedy-assassination conspiracy theorists has grown to include someone from within the Warren Commission itself: Charles N. Shaffer Jr., a former Justice Department prosecutor who served on the investigation’s staff in 1964 (he says he was dispatched by Attorney General Kennedy as “Bobby’s spy”) and went on to a headline-making career as a Washington-based criminal defense lawyer.

In interviews I have been conducting for a new edition of my 2013 book on the assassination, Shaffer told me there probably was a conspiracy in President Kennedy’s death, which makes him the first commission insider to say so publicly. He said he has no doubt that Oswald was the lone gunman in Dealey Plaza. Nor does he question the single-bullet theory, developed by the commission’s staff, which holds that one bullet passed through the bodies of both Kennedy and Texas Gov. John Connally. But he now suspects that the assassination was the work, ultimately, of organized-crime figures who somehow manipulated Oswald into gunning down the president in Dallas on Friday, Nov. 22, 1963, and then directed strip-club operator Jack Ruby to silence Oswald by killing him two days later.

“The Warren Report was an honest report, based on what we knew at the time,” Shaffer said. “But nothing should have been written in stone. There were later developments that convinced me that maybe we missed something.”