Tim Mapes, who for years served as the abrasive and sharp-tongued chief of staff to House Speaker Michael Madigan, was sentenced to 2 1/2 years in prison Monday for lying to a federal grand jury investigating his boss. In handing down the sentence, U.S. District Judge John Kness said he struggled at a fundamental level to understand how Mapes found himself in this position. “This is a very sad case to me because I don’t understand why you did what you did,” Kness said. “You were immunized in the grand jury and all you had to do was go in there and tell the truth.” Kness likened it to the mafia…