CHICAGO (CBS) — A Downers Grove North High School teacher voluntarily resigned and agreed to give up his teaching license, following an allegation that he sexually harassed a student about two decades ago.

The Board of Education accepted William Miller’s request during a meeting Monday evening. In addition to forfeiting his teaching license, Miller also had to agree to not teach in a K-12 setting again.

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William Miller, former band director at Downers Grove North, was accused of sexual harassment by a former student. (Photo provided to CBS)

“Prior to accepting his resignation, we conducted an investigation with the limited information available to us. We are unable to share details on any personnel matters related to current or former employees,” District 99 Supt. Dr. Hank Thiele said in a release to students, families and staff. “We will continue to cooperate fully with the Downers Grove Police Department. Their investigation remains open; no charges have been filed to date.”

Miller, who was the band director at Downers Grove North, was accused of sexual harassment by Jennifer Boudinot, a 1999 graduate. She took to Facebook to expose the alleged sexual misconduct of the long-term teacher.

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Boudinot said her initial Facebook post about Miller caused additional former students to come forward with their stories of inappropriate comments and acts — dating back almost 20 years.

“He used to go into online chat rooms with me and a friend of mine and just kind of talk about adult things,” she added.

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Miller had been on administrative leave since mid-November; he has been employed by District 99 since 1995.