It was nearly midnight on Oct. 15, 1890, as David Hennessy, the young New Orleans police chief, walked home in a drizzle after a late meeting of the police board. Hennessy was without his usual armed escort as he approached the Basin St. house he shared with his widowed mother. The chief had use for bodyguards. In New Orleans, he was the face of public hysteria about Italian immigrants, especially dusky Sicilians.