Frank Nitti was born in Sicily in the 1880s. He emigrated to New York City after the end of World War I, and later moved to Chicago, where he set up business as a barber, with a profitable sideline as a small-time jewel thief and fence. Nitti built an extensive network of associates in the Chicago underworld, and eventually came to the attention of Chicago crime boss John "Johnny The Fox" Torrio.
Under Torrio's successor, Al Capone, Nitti's reputation soared. Nitti ran Capone's Prohibition-busting liquor smuggling and distribution operation, importing whiskey from Canada and selling it through a network of speakeasies around Chicago. Nitti was one of Capone's top lieutenants, trusted for his leadership skills and business acumen.
Despite the portrayals of Nitti in movies and TV, Nitti was more about brains than brawn. Though I loved the scene in the 1987 Untouchables film... It was pure fiction. Nitti committed suicide... he wasn't tossed off a sky scraper.
Despite his nickname "The Enforcer", Nitti used Mafia "soldiers" and other underlings to commit violence rather than do it himself.
Not that Nitti was averse to using firearms - he had, in earlier days, been one of Capone's most trusted personal bodyguards - but as he rose in the organization, his business instinct dictated that he must personally avoid the "dirty work" - that was what the hitmen were paid for.
In 1931, both Frank Nitti and Al Capone were convicted of income tax evasion and sent to prison. However, Nitti only received an 18-month sentence while Capone was sent away for 11 years. Nitti was not a troublesome prisoner, but he found the year-and-a-half confinement in a cell horrifying because of the closed-in space. When Nitti was released in 1932, the media hailed him as the new boss of the Capone Gang.