Boss Tweed and Mae West both spent time in the old penitentiary on Welfare (now Roosevelt) Island, but there’s also this, about the rival Irish and Italian factions that controlled the place; Elizabeth Barlow (Rogers) tells the tale in The Forests and Wetlands of New York City:
"Joe Rao, a Harlem gangster, bootlegger and racketeer, who had been convicted of extortion in the Bronx soda water trade, headed the Italian faction. Edward Cleary was the Irish leader. They lived with their henchmen in different hospital wards in the manner of feudal barons, smoking expensive cigars and wearing silk shirts and underwear and costly dressing gowns. […] Heroin was brought into the prison by carrier pigeon."
La Guardia’s reformist Comish busted up the gangs inside, and the pen itself was demolished in 1936.
The soda water trade was mobbed up? Who knew?