CHICAGO (AP) — A federal jury in Chicago on Thursday convicted a former chief of staff to longtime Illinois House Speaker Michael Madigan of lying under oath to a grand jury to protect his once-powerful boss who is scheduled to go on trial on multiple corruption charges.

The 68-year-old Tim Mapes, who served for almost two decades as the Democrat’s chief of staff, was convicted of one count of perjury and one of attempted obstruction of justice. Obstruction alone carries up to 20 years in prison, while the perjury count carries up to five years behind bars.

The conviction strikes uncomfortably close to home for the now 81-year-old Madigan who, for decades, was one of the most powerful state legislative leaders in the nation. Many once thought he was untouchable because he was too smart, careful and well-connected.

Then, in 2022, he was indicted on charges that included racketeering and bribery.

At the Mapes trial, prosecutors told jurors he lied repeatedly when he testified in 2021 to a grand jury investigating Madigan and others. They said he specifically lied when he said he couldn’t recall any relevant details about Madigan’s ties to Michael McClain, who was a Madigan confidant.

Defense lawyer Katie Hill told jurors Mapes never intentionally misled the grand jury, saying he simply couldn’t remember many details. She likened the questions Mapes was asked to a pop quiz at a high school reunion and asked jurors if they would be able to remember the color of their prom corsages or who was class president their junior year.

Jurors deliberated for some five hours before returning with verdicts, the Chicago Tribune reported.

Federal jurors in May convicted four defendants of bribery conspiracy involving the state’s largest electric utility. Prosecutors said McClain, two former ComEd executives and a former utility consultant arranged contracts, jobs and money for Madigan’s associates to ensure proposed bills boosting ComEd profits became law.

A year before Madigan was indicted and amid speculation that he was a federal target, Madigan resigned from the Legislature as the longest-serving state House speaker in modern U.S. history.

The indictment accused Madigan of reaping the benefits of private legal work that was illegally steered to his law firm, among other things. He has denied any wrongdoing.