MINNEAPOLIS (WCCO) — The Anoka County Sheriff’s Office says there is a criminal investigation underway into a contracted teacher for St. Francis and Spring Lake Park schools.

According to Anoka County Sheriff’s Department Commander Paul Sommer, the investigation began after the St. Francis School District Interim Superintendent Troy Ferguson reported some concerning conduct that was alleged against the contracted teacher, identified as 48-year-old David Wayne Harrell of Chaska, Minn.

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Harrell, who works with hearing impaired students, was allegedly seen with a young student sitting on his lap. At that time, he was placed on leave and his access to students was prohibited.

“As part of that process, their technology coordinator was looking at that teacher’s computer and found thousands of images of children on the computer,” Sommer said.

Some of the images depicted young students posed in compromising positions, authorities said. That’s when the sheriff’s office began its own investigation and review of the data.

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Harrell was arrested for interference of privacy initially, but was later released without charges in order to complete a more extensive investigation.

Forensic computer detectives have since located thousands of photos on Harrell’s computer, some believed to be criminal in nature, authorities said. Detectives are looking to interview children depicted in some of the photographs. Some of the children were students of Harrell’s and others were students of the school Harrell had access to.

The investigation is ongoing and when completed, the case will be referred to the sheriff’s office, which will determine what, if any, criminal charges are appropriate.

The schools in question notified parents by letter and/or email Tuesday.

Harrell was not an employee of the St. Francis School District, but his services were contracted by St. Francis through his actual employer, School District 916.

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Harrell worked in both Spring Lake Park and St. Francis School districts for the past 10 years. He has written a children’s book, has no criminal history and, according to the St. Francis School superintendent, has no history of complaints or disciplinary actions.