A former Connecticut high school teacher was arrested Monday after police learned he had a trove of voyeuristic photos of students, including up-skirt photos of teen girls he took in his classroom, authorities said.

Christian Stevenson, 52, taught social studies and coached golf at Rockville High School in Vernon, where he resigned on Sept. 15 – the same day the allegations came to light – after 22 years, the Hartford Courant reported.

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The investigation began over the summer after the National Center for Missing and Exploited Children tipped off police that images believed to be child pornography were being transmitted from email accounts in Connecticut, the paper reported, citing police.

Former Rockville High School teacher Christian Stevenson, 52, was arrested Monday in Vernon.

Former Rockville High School teacher Christian Stevenson, 52, was arrested Monday in Vernon. (Vernon Police Department)

Investigators connected the images to Stevenson and got a warrant to conduct a forensic search on electronic items at his home, WFSB-TV reported. Some of the images found appeared to be taken inside the school. 

Many of the photos focused on the butts, chests or vaginal area of female students, who investigators said did not appear to know they were being photographed or recorded, according to the station.

Dozens of the photos were of two female students, who were ages 15 and 17 at the time, the reports said. 

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Stevenson was charged with importing child pornography, second-degree illegal possession of child pornography, eight counts of voyeurism and four counts of voyeurism with a child under 16. He faced an additional four counts of risk of injury to a minor and nine counts of disorderly conduct.

He is being held on $300,000 bail.