On 15 October 1890 New Orleans police chief David Hennessy was shot as he walked home in a light drizzle. He died the next morning. Deeply shocked, the people of New Orleans paid their respects (more filed past his casket at City Hall than had paid similar respects to former Confederate president Jefferson Davis, whose body lay in state there a few months earlier). City officials vowed to punish his killers.

Who Killed Hennessy?

Shortly before he died, Hennessy whispered to a bystander, "The Dagos did it." Hennessy was involved in a dispute between two rival groups of Italian immigrants working on the New Orleans docks. For years, Joseph Provenzano had a monopoly on the fruit trade from Central America. Provenzano owned ships that brought bananas, coconuts, and pineapples to New Orleans, where longshoremen in his pay unloaded the produce and...