I... For Icarus (1979)

After the recently re-elected President of a fictitious state has been assassinated, one of the members of the investigation committee refuses to sign the final report and is given the task of investigating once more. In the course of his search he finds evidence that casts serious doubt on the committee's "lone-gunman" theory... A very bold film that basically told the "JFK" story thinly disguised as having taken place not in the US.