On February 7, 1990, Sarno was one of 20 Chicago mobsters named in a 42-count indictment alleging racketeering. Sarno was jailed immediately but in an unusual move, was furloughed for several hours the following weekend to get married. Among the other defendants charged with various crimes in the same indictment were Chicago Outfit leaders Harry Aleman and Rocco Infelice.
Sarno was identified in the indictment as being a mob money collector of extortion payments and juice loans and as the owner of a tavern in Cicero, Illinois. During hearings on whether to give Sarno bond, he also was reported by federal investigators to have severely beaten a rival and acquaintance, Michael Giamarusti, whom Sarno had caught sleeping in Sarno's fiancee's apartment, in May 1989. An FBI agent testified that Giamarusti had required several stitches and dental work after Sarno beat him.
On February 15, 1990, Sarno was ordered held without bond. On May 15, 1990, however, Sarno was one of four defendants in the trial who was permitted by then-United States District Judge Ann Claire Williams to go free on bond. In January 1992, Sarno was convicted on charges of racketeering and running an illegal gambling operation, and on August 18, 1993, Sarno was sentenced to 6 1⁄2 years in prison for those crimes.
On January 22, 1993, Sarno was one of seven individuals indicted by federal officials in a separate indictment on additional extortion charges. Sarno was permitted to remain free pending a $100,000 cash and real estate bond posted in May 1990. Sarno was convicted of those charges and in 1996 was sentenced to 27 months in federal prison—18 months of which were to be served concurrently with his earlier sentence.
Sarno was released from federal prison on October 20, 1999.
In September 2004, Sarno was reported in the Chicago Sun-Times to be the leader of a mob street crew once led by Frank Calabrese, Sr., an assertion that Sarno's attorney deemed "a joke." In September 2007, after the convictions of a slew of Chicago-area mobsters in the Family Secrets trial, Sarno was identified by law enforcement sources in the Chicago Sun-Times as being a powerful reputed mobster in the Chicago Outfit, along with Joseph Andriacchi, Al Tornabene, Frank "Toots" Caruso, Marco D'Amico and John DiFronzo.
In the summer of 2008, Sarno's house in Westchester, Illinois was among the locations raided by federal agents investigating a February 23, 2003 pipe-bombing incident outside of a Berwyn, Illinois video and vending machine business. Sources told the Chicago Tribune that Sarno was the target of the search, and that a large amount of cash was recovered during the search. Sarno was referred to in the indictment of two men, Samuel Volpendesto and Mark Polchan, in connection with the crime as "Outfit Member A." Sarno also was referred to by Volpendesto on undercover tapes that federal investigators had made as "the Large Guy"—a reference to Sarno's large size.
In September 2008, Chicago Sun-Times federal courts reporter Steve Warmbir wrote that "this (investigation) appears to be possibly be building toward a reputed high-level mobster, Mike Sarno."
On May 28, 2009, Sarno was indicted by the federal government and accused of leading an illegal gambling ring and playing a key role in the 2003 pipe-bombing incident. Six others, including 85-year-old Volpendesto, also were charged with racketeering conspiracy. The ring was alleged to have pulled off jewelry heists, stolen cars, committed arson, intimidated witnesses, and bombed a competitor's video poker business. Sarno allegedly oversaw nine robberies and thefts that yielded more than $1.8 million. In addition to Volpendesto and Polchan, the others charged were Dino Vitalo, a Cicero, Illinois police officer who was alleged to have tipped the group off to police activity; James Formato, a former Berwyn, Illinois police officer, Mark Hay, and Volpendesto's 46-year-old son, Anthony Volpendesto.
Federal investigators have referred to Sarno as "Outfit Member A" in court filings related to the pipe bombing. He also has been referred to as "Big Mike," "Large" and "The Large Guy."
On December 22, 2010, Sarno was convicted on racketeering charges related to his running the illegal gambling ring and playing a role in the 2003 pipe bombing. At that point, Sarno's bond was revoked, and he was imprisoned in Chicago's Metropolitan Correctional Center. Sarno then was scheduled to be sentenced on February 8, 2012.
On February 8, 2012, U.S. District Judge Ronald A. Guzman sentenced Sarno to 25 years in prison on the racketeering charges. Immediately prior to the sentencing, Sarno told Guzman, "as I stand before you, I have some regrets." He tried to continue with a statement before breaking into tears, allowing his defense attorney, Jeffrey Steinback, to complete his statement. As Guzman handed down the sentence, the judge told those in court that "the hardship to the defendant and to his family, the court has no doubt is real and is -- the word 'unfortunate' seems insufficient. They of course have been accused and convicted of nothing." However, Guzman noted that a stiff sentence was needed both to protect the public and to prevent anyone who would seek to "follow in the defendant's footsteps." Guzman also told Sarno and those gathered in the courtroom that "the defendant from the moment he was released (from prison, in 1999) embarked on a trail of criminal enterprises."
Sarno is currently incarcerated in FCI Petersburg in Hopewell, Virginia with a projected release date of 2032.