I agree with John Newman, this is significant, especially given what we now know about counterintelligence chief James Angleton’s monitoring of Lee Oswald between 1959 and 1963.
At the time of the assassination, Dallas Mayor Earle Cabell, brother of one-time Deputy Director of Central Intelligence Charles P. Cabell, had been a CIA asset since 1956. It is worth noting that Kennedy dismissed CIA Director Allen Dulles in November 1961, and that Earle Cabell’s brother Charles left the CIA on January 31, 1962, after Kennedy forced him to resign. Thus, both Dulles and Charles Cabell were no longer working for the CIA on November 22, 1963, when Kennedy was killed.
Source: Dallas Mayor During JFK Assassination Was CIA Asset – WhoWhatWhy