From Wikipedia

Crime Inc.
Episode Six

Make it Legitimate

New Orleans was the site of the first Mafia incident in the United States that received both national and international attention. On October 15, 1890, New Orleans Police Superintendent David Hennessy was murdered execution-style. It is still unclear whether Italian immigrants actually killed him or whether it was a frame-up against the reviled underclass immigrants. Hundreds of Sicilians were arrested on mostly baseless charges, and nineteen were eventually indicted for the murder. An acquittal followed, with rumors of bribed and intimidated witnesses. The outraged citizens of New Orleans organized a lynch mob after the acquittal, and proceeded to kill eleven of the nineteen defendants. Two were hanged, nine were shot, and the remaining eight escaped. The lynching was the largest mass lynching in American history.