The Warren Commission after 40+ years: still right
27 September 1964 saw the release of the Warren Commission Report on the JFK assassination. Hailed for a short period of time, the report became in the 1960s a victim of the paranoia of the counter-cultural crack-up.
The turning point came, paradoxically, through Oliver Stone's 1991 crack-pot movie JFK. Stone attempted to rehabilitate a discredited New Orleans prosecutor who tried to prove a conspiracy to assassinate the president--which prosecutor in turn had been brutally exposed by the national news media. The news media turned on the movie, counter-attacked, demolished Stone's case, and gave key publicity to the best book ever written on the JFK assassination: Gerald Posner's irrefutable Case Closed.
The case against Oswald was basically open-and-shut: all the surviving bullet and bullet fragments came exclusively from Oswald's rifle. The rifle had Oswald's fingerprints on it. Oswald fled the scene of the crime immediately after the shooting; when stopped by a police officer, Oswald shot him in cold blood. Oswald then fled to a movie theater; and when approached by another police officer, he tried to shoot him as well--and failed only because his revolver jammed.
For those determined to believe in conspiracy theories, the theory with the most evidence is this one: Jackie did it. It's not well known, but Jackie had a distant relative, George De Mohrenschildt, who was one of Oswald's few friends in Dallas. The theory is simple. Jackie: "I want that cheating husband of mine dealt with!" George: "I know just the man who can help." No, of course, I'm not serious--but there's more hard evidence for that theory than for any other theory out there.
Of course, I'm leaving out the solution offered by one of the finest series in the history of television...for the documentation on the cigaret-smoking man as the true assassin, see The X-Files (4x8).
[Partial secret full disclosure: GrenfellHunt is linked to a commission staffer...so I might be part of the conspiracy...]