Elmer L. Irey, the first chief of the Special Intelligence Unit at the Treasury Department, was the twentieth century’s greatest law enforcement figure. He accomplished what J. Edgar Hoover wouldn’t and Eliot Ness couldn’t: he successfully prosecuted ruthless, murderous bosses who ruled U.S. cities from the 1920s through the 1940s. Irey’s takedown of Al Capone is still the landmark law enforcement achievement in U.S. history. Those whom Irey and his branch brought to justice reads like a who’s who of crime and politics: Boss Tom Pendergast in Kansas City, Huey Long’s gang in Louisiana, ‘Nucky’ Johnson in Atlantic City, Morris Kleinman of Cleveland’s Mayfield Road gang, and Leon Gleckman, the ‘Al Capone of St. Paul’. Irey also indicted businessman and publisher, Moses L. Annenberg, a cagey racketeer who was one of the nation’s wealthiest figures. Prohibition was an era of rampant corruption, organized crime, and compromised officials. Attorney General Homer Cummings sent Hoover and the G-men after bank robbers instead of racketeers, even though Charles ‘Lucky’ Luciano, then the Mafia’s boss of bosses, stole more cash in one week than celebrity bandits like John Dillinger did during their entire careers. Irey’s work with Tom Dewey, using investigative accountants to pursue New York’s racketeers, later led to putting Luciano behind bars. The Irey-led investigation of the stagehands’ union extortion plot in Hollywood resulted in the first ever takedown of a Mafia-aligned group - fifty years before U.S. Attorney Rudolph Giuliani went after the Five Mafia families.