In this still from footage taken by presidential aide Dave Powers and photographed from a television screen, President John F. Kennedy, accompanied by his wife, Jacqueline, waves from his limousine in Dallas on Nov. 22, 1963.
According to a CBS News poll released this month, 61 percent of Americans say they believe multiple people were involved in a conspiracy to assassinate Kennedy, while 20 percent think Oswald acted alone.
Belief in a conspiracy, though strong, has declined in recent years. In 1998, just 10 percent of Americans believed Oswald had acted alone. And while 56 percent currently believe there was an official cover-up to keep Americans from learning the truth about JFK's death, that number was far larger -- 81 percent -- in 1993.
Powers ran out of film before the motorcade entered Dealey Plaza where the fatal shots where fired.