CHICAGO (CBS) — Illinois House Speaker Mike Madigan has fired a longtime political aide over allegations of sexual harassment.

In a statement Monday morning, Madigan said his office was notified of the allegations against aide Kevin Quinn in November, and that he had his chief counsel conduct an investigation. Quinn is the brother of Ald. Marty Quinn (13th), a former Madigan campaign staffer.

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“A courageous woman made me aware that a high-ranking individual within my political operation had previously made unwanted advances and sent her inappropriate text messages. I immediately consulted with my attorney, Heather Wier Vaught, and directed her to conduct a thorough investigation,” Madigan said.

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According to Madigan’s office, following a series of interviews, Wier Vaught “recently came to the conclusion that the individual engaged in inappropriate conduct and failed to exercise the professional judgment I expect of those affiliated with my political organizations and the Office of the Speaker.

“As a result, long-time aide Kevin Quinn is no longer an employee of any of my political committees. Mr. Quinn has worked with my political offices for nearly 20 years. While this is the only allegation of such conduct, Mr. Quinn also recently pled guilty to misdemeanor disorderly conduct. Based on the culmination of events, Alderman Marty Quinn and I decided that Kevin should no longer be affiliated with the political organization. For the record, Kevin was previously an employee of my State office, and he will not be returning to that role,” Madigan said.

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The speaker said his office also is implementing a number of recommendations Wier Vaught made to improve methods of reporting and responding to allegations of sexual misconduct.