A Barron County middle school teacher is charged with sexually assaulting a teenager.

Thirty-eight-year-old Nathan E. Cox faces one felony count of second-degree sexual assault of a child.

Prosecutors say the sexual contact happened in Barron County last summer.

And the Barron County Sheriff says his department is treating the case as a priority.

Parents with children in the Prairie Farm School District got letters letting them know a teacher was in trouble.

The district's administrator says Nathan E. Cox teaches math to students in grades five through nine.

He also coaches middle school track and wrestlers of all ages.

"The district continues to cooperate with the authorities," said Prairie Farm School District Administrator Donald Hauck. "Our thoughts are with our students at this time."

School leaders say Cox is on administrative leave without pay while prosecutors move forward with the case against him.

In the complaint, the victim, who was 13 at the time says she and Nathan Cox had a sexual encounter in his vehicle and at his house.

"It's very disheartening, this type of case," said Barron County Sheriff Tom Richie. "A very difficult one to investigate. But we're satisfied we have a good case, and we will be moving forward with the justice process."

The complaint was filed Friday and details intimate contact including kissing and touching.

The whole thing has people working and attending the school in shock.

Administrator Donald Hauck says the district is offering counseling for any students who want it.

"We have a teacher in his place, and our students will be well-taught for the reamining time of the year," Hauck said.

Neither Hauck nor Sheriff Richie will comment on whether the girl involved is or ever was a student at Prairie Farm.

We also tried to contact Cox at his home for comment but were unable to talk to him.

Cox is scheduled for his initial appearance in Barron County Circuit Court on Wednesday.