Since the assassin, Lee Harvey Oswald, was killed by a man named Jack Ruby almost immediately after murdering Kennedy, Oswald's motive for assassinating the president remained unknown. Seven days after the assassination, Johnson appointed the President's Commission on the Assassination of President Kennedy to investigate Kennedy's death. The commission was led by Chief Justice Earl Warren and became known as the Warren Commission. It concluded that Oswald had acted alone and that the Secret Service had made poor preparations for JFK's visit to Dallas and had failed to sufficiently protect him.
The circumstances surrounding Kennedy's death, however, have since given rise to several conspiracy theories involving such disparate characters as the Mafia, Cuban exiles, military leaders and even Lyndon Johnson. The Warren Commission's conclusion that Oswald was a "lone gunman" failed to satisfy some who witnessed the attack and others whose research found conflicting details in the commission's report. Critics of the Warren Commission's report believed that additional ballistics experts' conclusions and a home movie shot at the scene disputed the theory that three bullets fired from Oswald's gun could have caused Kennedy's fatal wounds as well as the injuries to Texas Governor John Connally, who was riding with the president in an open car as it traveled through Dallas' Dealey Plaza that fateful day. So persistent was the controversy that another congressional investigation was conducted in 1979; that committee reached the same conclusion as the Warren Commission.
During its almost year-long investigation, the Warren Commission reviewed reports by the Federal Bureau of Investigation, Secret Service, Department of State and the attorney general of Texas. It also pored over Oswald's personal history, political affiliations and military record. Overall, the Warren Commission listened to the testimony of 552 witnesses and even traveled to Dallas several times to visit the site where Kennedy was shot. The enormous volume of documentation from the investigation was placed in the National Archives and much of it is now available to the public. Access to Kennedy's autopsy records, though, are highly restricted. To view them requires membership in a presidential or congressional commission or the permission of the Kennedy family.