Al Capone "Big Jim" Colosimo as an enforcer. Capone began in Chicago as a bouncer in a brothel, where he contracted syphilis. Timely use of Salvarsan probably could have cured the infection, but he apparently never sought treatment. In 1923, he purchased a small house at 7244 South Prairie Avenue in the Park Manor neighborhood on the city's south side for . In the early years of the decade, his name began appearing in newspaper sports pages where he was described as a boxing promoter. Torrio took over Colosimo's crime empire after Colosimo's murder on May 11, 1920, in which Capone was
Al Capone suspected of being involved. Torrio headed an essentially Italian organized crime group that was the biggest in the city, with Capone as his right-hand man. He was wary of being drawn into gang wars and tried to negotiate agreements over territory between rival crime groups. The smaller North Side Gang led by Dean O'Banion (also known as Dion O'Banion) was of mixed ethnicity, and it came under pressure from the Genna brothers who were allied with Torrio. O'Banion found that Torrio was unhelpful with the encroachment of the Gennas into the North Side, despite his pretensions to be a settler