ROLLING MEADOWS (CBS) — A former teacher at the Schaumburg Christian school on Wednesday denied charges he masturbated in front of students while teaching his math class.

Paul LaDuke, 75, was arrested after a student told another teacher about the alleged incident. LaDuke appeared in court and pleaded not guilty to nine counts of felony exploitation of a child–a charge that carries a maximum three-year prison term.

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An attorney for LaDuke says his client may have been struggling with dementia when he admitted to police he engaged in similar actions over a 10-year-period.

LaDuke was arrested after a student at the Schaumburg Christian School told another teacher that LaDuke unzipped his pants while sitting behind a podium, then masturbated while his students were in the classroom.

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Several students later interviewed by police offered similar accounts, authorities have said.

LaDuke, who remains free on bond, was fired from his teaching job after the allegations first surfaced.

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The Sun-Times Media Wire contributed to this report