Thirty percent of Americans believe that Oswald, who was apprehended by Dallas police hours after Kennedy was shot on Nov. 22, 1963, was the lone gunman in the murder. The Warren Commission, the official government investigation into the assassination, concluded that Oswald acted alone. Oswald was killed by Jack Ruby two days after the Kennedy assassination and therefore never stood trial, leaving many questions unanswered.

Americans were skeptical about the “lone gunman” theory almost immediately after Kennedy was killed. In a poll conducted Nov. 22-27, 1963, Gallup found that 29% of Americans believed one man was responsible for the shooting and 52% believed others were involved in a conspiracy. A majority of Americans have maintained that “others were involved” in the shooting each time Gallup has asked this question over the past 50 years, except December 1966, when exactly half of Americans said someone in addition to Oswald was responsible.

By 1976, Americans’ belief in the conspiracy theory swelled to 81%. The percentage believing more than one person was involved remained high for decades, amid numerous published reports and books that alleged a conspiracy. The Oscar-winning film “JFK” implied that President Lyndon Johnson may have been involved in such a conspiracy.