Dearborn schools officials said a substitute teacher accidentally played a pornographic video to a class of seventh-graders.

The teacher was attempting to play a video of Lewis and Clark for a U.S. history class on March 13 when the X-rated video showed on the screen instead, according to a school official.

David Mustonen, Dearborn schools communication director, said Wednesday that the teacher was attempting to access a video from a website on a school district computer, which was connected to a projector.

"The substitute teacher that was in the classroom was unaware that this video was there," David Mustonen, Dearborn schools communication director, told WJBK.

It is unclear exactly how the video surfaced but Mustonen said there's no evidence that anyone was pranking the teacher.

Mustonen said that a personnel investigation by Dearborn police and the school district was complete. However a separate investigation is ongoing by the district's information technology department.

Mustonen could not comment about the technical investigation but said part of it includes looking at how the video was able to slip through the district's internet filtering software, which he said is "working every day."

The school district decided not to rehire the substitute teacher because there's no confirmation of the video's origin.

According to WJBK, Dearborn police found "no criminal intent."

The substitute was hired under a contract through a substitute teacher service, allowing the district to individually select substitutes.

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