On Nov. 22, 1963, the nation was traumatized by the assassination of President John F. Kennedy in Dallas. Two days later, a second shock followed, when suspected assassin Lee Harvey Oswald was ambushed and shot to death by Jack Ruby while in police custody before he could be brought to trial. Kennedy's successor, President Lyndon Johnson, appointed a special commission, headed by U.S. Supreme Court Chief Justice Earl Warren, to figure out what had happened. The Warren Commission's report, issued in September 1964, concluded that Oswald not only had fired the shot that killed Kennedy from a window in the Texas Book Depository, but also that he had acted alone — as had Ruby, his killer [source: Lewis].
But in the years that followed, skeptics attacked the massive Warren Commission report as an incomplete investigation. They were right. In 1967, an article by syndicated columnists Drew Pearson and Jack Anderson posed the theory that Kennedy had been killed not by a lone gunman, but in retaliation for U.S. Central Intelligence Agency (CIA) plot to assassinate Cuban dictator Fidel Castro [source: Select Committee]. The CIA somehow had neglected to inform the commission of those plots, even though both Oswald and his killer Ruby had a number of conspicuous links to Cuba. For example, Oswald had attempted to contact the Cuban embassy in Mexico City at one point [source: Warren Commission Report].
Those and other omissions led a House committee to conclude in 1979 that Kennedy "was probably killed as a result of a conspiracy," though it could not determine who was involved [source: Select Committee]. The mystery continues to this day.