Jack Ruby (born Jacob Leon Rubenstein; March 25, 1911[?] – January 3, 1967) was a nightclub operator in Dallas, Texas. On November 24, 1963, Ruby fatally shot Lee Harvey Oswald, who was in police custody after being charged with the murder of President John F. Kennedy two days earlier. A Dallas jury found Ruby guilty of murdering Oswald, and Ruby was sentenced to death. Later, Ruby appealed his conviction, had it overturned and was granted a new trial. As the date for his new trial was being set, Ruby became ill and died of a pulmonary embolism due to lung cancer, being constitutionally presumed innocent at the time.

Many researchers contend Ruby was involved with major figures in organized crime, and conspiracy theorists widely assert that Ruby killed Oswald as part of an overall plot surrounding the assassination of President Kennedy.

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