It may not have been an actual empire over which the Duff family presided in their native Chicago. But it was hardly a Mom-and-Pop operation either. Family patriarch John Duff, Jr., his wife Patricia, and their sons had grown wealthy over the decades, having cultivated ties both to City Hall and the underworld. But the past few years have seen the Duffs fall upon hard times, after lengthy investigations by the Labor Department’s Office of Labor-Management Standards (OLMS) and Office of Inspector General, plus the FBI and the IRS. The most important chapter may have been closed in U.S. District Court this May 18-20, with the sentencing of four persons for fraud, money laundering and racketeering.