HOLLIS, Okla. (AP) -- A former middle school teacher has pleaded guilty to having sex with a student, and the boy's father says in a lawsuit that school officials covered up the crimes.

The Oklahoman reported Tuesday ( http://bit.ly/1IapVx8 ) that Jennifer Caswell pleaded guilty Monday to second-degree rape and other charges in Harmon County District Court. Sentencing was set for Aug. 31.

The boy's father says in a federal lawsuit that local school officials let Caswell resign and keep her teaching credentials. He is seeking $1 million for pain, suffering and his son's mental and emotional anguish. The district denies wrongdoing.

"The district's overall position is that they acted appropriately once they were aware of an issue," lawyer Andy Fugitt told the newspaper.

The boy was 15 at the time of the crimes; Caswell is 29. She didn't respond to requests to comment on the allegations and her lawyer was in court Tuesday and unavailable to comment on her behalf.

The father alleges at least two people saw Caswell engaged in sexual acts with his son in her classroom, when she taught under the name Jennifer Sexton. After she resigned in April 2014, she had sex with the boy in a vehicle, her house and the boy's father's house, according to prosecutors. After the woman followed him to Mississippi, where he had been sent to say with his mother, the boy began cooperating with authorities.

The Associated Press does not generally name victims of sexual crimes. It is not identifying the boy's father to shield the son's identity.

The lawsuit, filed in April, says the boy's grades have suffered and he has become withdrawn and quiet.

Caswell appeared on a syndicated talk show last month and said she was "not a rapist." She pleaded guilty Monday to three counts of second-degree rape, two counts of enticing a child and one count of forcible sodomy.

"I didn't force anything. I didn't manipulate. I didn't take advantage," she said on the "Dr. Phil" show. Her lawyer told The Oklahoman that she was paid for her appearance.

Caswell has since had her teaching credentials revoked.