Kenneth O'Donnell was JFK's Chief of Staff, among the group known as Kennedy's "Irish Mafia." O'Donnell was with Jack Kennedy through his entire time in office ... and he was on Air Force One in Dallas, at Jacqueline Kennedy's side, as Lyndon Johnson got sworn in. When John F. Kennedy was assassinated, LBJ asked Ken O'Donnell to stay on and work with him through the first nine months of his administration, to help the country transition and heal,...