Gerald Leo Posner is an American investigative journalist and author of thirteen books, including Case Closed: Lee Harvey Oswald and the Assassination of JFK (1993), which explores the John F. Kennedy assassination, and Killing the Dream: James Earl Ray and the Assassination of Martin Luther King, Jr. (1998), about the assassination of Martin Luther King, Jr. A plagiarism scandal involving articles that Posner wrote for The Daily Beast and his book Miami Babylon arose in 2010.

On November 22, 1963, John F. Kennedy, the 35th president of the United States, was assassinated while riding in a presidential motorcade through Dealey Plaza in Dallas, Texas. Kennedy was in the vehicle with his wife, Jacqueline, Texas Governor John Connally, and Connally's wife, Nellie, when he was fatally shot from the nearby Texas School Book Depository by former U.S. Marine Lee Harvey Oswald. The motorcade rushed to Parkland Memorial Hospital, where Kennedy was pronounced dead about 30 minutes after the shooting; Connally was also wounded in the attack but recovered. Vice President Lyndon B. Johnson was hastily sworn in as president two hours and eight minutes later aboard Air Force One at Dallas Love Field.