Capone’s base of operations, until 1928, was a suite of rooms at the Metropole Hotel located at 2300 S. Michigan Avenue. Thereafter, and while Frank Nitti was at least publicly running "the outfit" in the 1930s, head offices were at the Lexington Hotel, just down the street at 2135 S. Michigan.
Nitti began his career as a barber. Proving his value in other ways, however, held him in good stead with Al. His specialty was smuggling Canadian whiskey into Chicago. He was soon second-in-command of Capone’s organization.
The Enforcer’s style was, essentially, "Do business with us and you won’t get hurt." While he spent some time behind bars in Cook County’s "Division I," he didn’t stay there long.
While Capone was in prison, Nitti was shot six times (in December of 1932) during a police raid (of Capone’s headquarters) by Anton Cermak’s personal detail. (Cermak was the mayor of Chicago at the time.) Although gravely injured, Nitti recovered.
About two months later, Cermak was assassinated by Giuseppe ("Joseph") Zangara, a man who (according to the official story) was likely aiming for President-elect Franklin Delano Roosevelt. In an interview with Raymond Moley - an FDR colleague who wrote much of the President's first inaugural address - Zangara seems to acknowledge that he intended to shoot the President-elect.
The story has always persisted, however, that Cermak was killed in retaliation for Nitti’s attempted murder. And a book published in 2001, Capone’s Mob Murdered Roger Touhy, claims that Secret Service Agency documents prove Nitti’s outfit stalked Cermak before his death. We may, of course, never really know the truth.
One thing we do know for sure. The Enforcer had little stomach for life behind bars. In 1943, while facing more criminal charges, Nitti killed himself.