Lee Harvey Oswald, Part I was the first part of a two-episode story arc, which was originally shown as a two-hour episode. The Season opening episode of Season 5 of Quantum Leap, it was also the 76th overall series episode. Written by series creator and executive producer Donald P. Bellisario, the episode, which was directed by James Whitmore, Jr., first aired on NBC-TV on September 22, 1992.
Sam leaps into various points in the life of Lee Harvey Oswald (played by Willie Garson) in an effort to seemingly prevent him from killing President John F. Kennedy or find the truth about the events that day. However, the objective is made more complex by the fact that their minds are merging. Sam starts to believe he is Oswald. If Al can't bring Sam back, it will be Sam Beckett who pulls the trigger on Kennedy that fateful day in Dallas. In the end, Oswald is the lone assassin of JFK (Al speculating that people made up the idea of a conspiracy rather than face the idea that we are all still so vulnerable that one man could kill the President that easily). Sam makes a final leap into U.S. Secret Service agent Clint Hill who climbed on the back of the President's limousine during the assassination.In the episode dénouement,Al reveals that an alternate history had previously occurred where Jackie Kennedy (played by Karen Ingram) also died and Sam's actual mission was to save her.