Iowa City, Iowa, basketball coach Greg Stephen pleaded guilty to charges involving the sexual exploitation of at least 400 boys.

Over several years, Stephen took videos of himself fondling players as they slept, made videos of them while they were nude, and even posed as girls on social media to exploit them.

He had a hard drive with folders for at least 400 boys with explicit photos and videos of them.

Stephen also disguised cameras in smoke detectors and bath towels to spy on children.

A popular youth basketball coach admitted to sexually exploiting at least 400 children over several years.

Greg Stephen, coach and co-founder of the Iowa Barnstormers of the Amateur Athletic Union, pleaded guilty to seven charges, pleaded guilty to seven charges, including sexually exploiting minors and possessing and transporting child pornography. Stephen revealed that he'd taken videos of himself fondling young players as they slept, made videos of them showering, and posed as girls on social media to trick them into masturbating on camera.

Stephen, 42, led a prestigious Adidas-sponsored program for the top players in the state between the ages of nine and 17, viewed as a feeder for top college basketball teams in the country. He was arrested in March, shocking the state's basketball community.

Greg Stephen's mugshot. Cedar Rapids federal court

In a plea agreement filed Thursday in a federal court in Cedar Rapids and viewed by the Associated Press, Stephen revealed new details about his abuse of hundreds of children. He pleaded guilty to sexually exploiting minors and possessing and transporting child pornography, in addition to five other crimes.

As a condition of his plea deal, Stephen will be allowed to appeal the decision of the courts to admit evidence discovered by his brother-in-law, Vaughn Ellison. In February, Ellison — working on a remodeling job at Stephen's home — discovered a secret recording device hidden within the walls.

Stephen said he maintained a hard drive that had folders for at least 400 different boys, each with explicit photos and videos of the children in his program. He also disguised smoke detectors, and bath towel hooks in his homes as cameras, and on at least one occasion drugged a boy in his care, according to the plea agreement.

If convicted on the charges, Stephen will face a minimum of 15 years to up to 120 years. The Iowa Division of Criminal Investigation has said that it's still willing to talk to new victims who may have yet come forward.

The Stephen case follows the conviction of Larry Nassar, the former University of Michigan sports doctor, who is serving decades in prison after hundreds of women accused him of sexual assault. The case that raised awareness about sexual abuse in youth sports programs and sent a shockwave through the entire USA Gymnastics organization.