Coniston massacre
The board sat for 18 days in January 1929 to consider three incidents (Brooks, Morton and Tilmouth) that resulted in the deaths of Aboriginal people, and in one more day, finished its report, finding that 31 Aboriginal people had been killed and that in each case the death was justified.
CIA Kennedy assassination conspiracy theory
John F. Kennedy, the 35th President of the United States, was assassinated in Dallas, Texas, on November 22, 1963. Various agencies and government panels have investigated the assassination at length, drawing different conclusions. Lee Harvey Oswald is accepted by official investigations as the assassin, but he was murdered by Jack Ruby before he could be tried in a court of law. The discrepancies between the official investigations and the extraordinary nature of the assassination have led to a variety of theories about how and why Kennedy was assassinated. 
The House Select Committee on Assassinations (HSCA) concluded in 1979 that Oswald assassinated Kennedy, but that a conspiracy was probable. The committee did not implicate U.S. Intelligence agencies. Their conclusion was reached almost entirely because of the results of forensic analysis of a police dictabelt, which supposedly recorded the sound of a fourth bullet being fired in Dealey Plaza.