Jack "Machine Gun" McGurn, one of the toughest hitmen of Chicago Outfit boss Al Capone, recruited Accardo into his crew, along with long time associate Tony Mazlack of Gary, Indiana.

[5][4] In later years, Accardo boasted over federal wiretaps that he participated in the infamous 1929 St. Valentine's Day Massacre in which, allegedly, Capone gunmen murdered seven members of rival Bugs Moran's North Side Gang.

Accardo also claimed that he was one of the gunmen who murdered Brooklyn gang boss Frankie Yale, again by Capone's orders to settle a dispute.

However, most experts believe Accardo had only peripheral connections, if any, with the St. Valentine's Day Massacre and none whatsoever with the Yale murder, which was most likely committed by Gus Winkler, Fred Burke, and Louis Campagna.

However, on October 11, 1926, Accardo may have participated in the assassination of Northside gang leader Hymie Weiss near the Holy Name Cathedral in Chicago.

Accardo soon developed a variety of profitable rackets, including gambling, loansharking, bookmaking, extortion, and the distribution of untaxed alcohol and cigarettes.

As the decade progressed, senior members of the Outfit were investigated and charged with using the threat of strike action by the labor unions they controlled to extort millions of dollars from Hollywood studios.

Paul "The Waiter" Ricca, who had been the de facto boss since Capone's imprisonment, took the role officially and named Accardo as underboss.

[4][7] Under Accardo's leadership in the late 1940s, the Outfit moved into slot and vending machines, counterfeiting cigarette and liquor tax stamps, and expanding narcotics smuggling.

For example, when professional wrestlers Lou Albano and Tony Altomare, wrestling as a Mafia-inspired tag team called "The Sicilians", came to Chicago in 1961, Accardo persuaded the men to drop the gimmick to avoid any mob-related publicity.

Unlike Accardo, the widowed Giancana lived an ostentatious lifestyle, frequenting posh nightclubs and dating high-profile singer Phyllis McGuire.

In June 1975, after spending most of his Outfit-exile years in Mexico and unceremoniously being booted from that country, Giancana was murdered in the basement apartment of his home, in Oak Park, Illinois, while cooking Italian sausages and escarole.

The six-bedroom, six-bath home he owned on Franklin Avenue in River Forest contained two bowling lanes, an indoor swimming pool, and a pipe organ.

When he started receiving attention from the IRS about his apparent high lifestyle, he bought a ranch home on the 1400 block of North Ashland Avenue in River Forest and installed a vault.

His neighbor and friend physician Jim Carto lived across the street off Ashland Ave in the Mars Candy Mansion, and was rumored to have assisted in providing medical care.

[9] In the late 1970s, Accardo bought a home in Palm Springs, California,[19][20] flying to Chicago to preside over Outfit "sit-downs" and mediate disputes.