Known as "The Enforcer," Frank Nitti was a key player in the Chicago organized crime syndicate headed by Al Capone. Nitti was born in Naples, Italy, around 1896, and as a young man in Chicago's close-knit Italian community, he became a barber and a "fence" for stolen goods. His connections brought him to the attention of Capone's organization around 1920. During the next decade, Nitti advanced his career by arranging large-scale smuggling operations of Canadian whiskey into Illinois. When Capone was sent to jail in 1929, the local press described Nitti as Capone's successor, but in reality the syndicate was largely controlled by Paul "The Walter" Ricca. In 1930, Nitti went to jail for several months on an income-tax evasion charge. He was claustrophobic, however, and the experience was a traumatic one for him. He emerged as one of the most feared criminals in Chicago. He was indicted in 1940 for interfering in a bartenders' union, but the local's president refused to testify and the case was dismissed.

Nitti and other American mobsters also had ties to the International Alliance of Theatrical Stage Employees (IATSE) union. In 1943, government agents charged Nitti and eight others with trying to extort $1 million from four different motion-picture companies by threatening to instigate union trouble at the studios. At a meeting held at Nitti's suburban Chicago home, Ricca forced Nitti to take the blame for the charges, and he refused. Just before the federal grand jury indictment was handed down on March 19, 1943, Nitti, drinking heavily, shot himself near railroad tracks outside his home in North Riverside, Illinois.