That question is asked in this article , one of a series by Michael Salla, Ph.D. Salla's thesis is based on the dubious MJ-12 documents. He also features the McCone-Rowley document, first introduced to the world by me, which he refers to as a "declassified CIA document."
There is more evidence to directly implicate Angleton in the Kennedy assassination. Lee Harvey Oswald was among a small group of American citizens to have defected to the Soviet Union in 1959. The CIA established a file on Oswald in 1960, but some authors claim that CIA counterintelligence were monitoring Oswald even earlier, and that Angleton was directly involved through an intermediary. A declassified CIA document later confirmed that Oswald was trained by the CIA in 1957 for Soviet assignments.