INDIANAPOLIS » The head of an Indianapolis gymnastics academy has been charged with child molestation and child pornography after authorities said thousands of explicit images of children were found in his possession.

Marvin Sharp, 48, faces four counts of child molestation and three counts of sexual misconduct with a minor filed by Marion County prosecutors, who allege that he repeatedly fondled a girl while he was her coach.

Federal prosecutors who charged Sharp with knowing receipt of child pornography and knowing possession of child pornography said investigators found thousands of sexually explicit images of minors in locked safes in his Indianapolis home Saturday and more in a file cabinet at his business, Sharp’s Gymnastics Academy.

Sharp was arrested Monday on preliminary charges and remained jailed Tuesday. It was unclear whether he had an attorney who could speak on his behalf.

A probable cause affidavit filed with the local charges state that Sharp repeatedly fondled or touched a girl he had coached and that abuse began when she was 12 and continued for about two years.

Sharp repeatedly photographed the girl in a room at his gymnasium and allegedly fondled her while adjusting her clothing, the affidavit states. She told investigators Sharp "would constantly ‘fix her underwear’" and touch her during the photo sessions. In one session, she said Sharp made her wear a straightjacket, and on other occasions asked her to pose "provocatively" in clothing he had provided her, the document says.

The girl told authorities she feared Sharp would "kick her out of the gym or hurt her" if she didn’t do as asked. She later told her mother about the events during the photo shoots, court documents say.

"It is a parent’s worst nightmare that someone whom we entrust with care and guidance of our children — whether a coach, teacher, or otherwise — would abuse that trust and harm our children," Marion County Prosecutor Terry Curry said in a statement.

The U.S. attorney’s office in Indianapolis said in its charging documents that investigators found some of the thousands of child porn images after breaking into safes at Sharp’s home and business. Prosecutors said they believe he obtained the images from other persons or sources "and intentionally saved it."

Federal court documents said "the files appear to have been accumulated and stored over a very long period of time." The images are being analyzed to determine whether any were produced by Sharp, court documents state.

USA Gymnastics issued a statement saying it is cooperating with law enforcement in the investigation.

"Athlete safety is the top priority for USA Gymnastics, and these charges contradict USA Gymnastics’ philosophy, standards and policy," the statement said.