HUNTSVILLE, Texas (CBSDFW.COM/AP) – Disgraced ex-sports doctor Larry Nassar and a former trainer were charged with sexual assault Friday following an investigation involving an elite gymnastics center in Texas.

A grand jury indicted Nassar on six counts of second-degree sexual assault of a child, Walker County prosecutor Stephanie Stroud announced during a news conference.

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Larry Nassar sits in court listening to statements before being sentenced by Judge Janice Cunningham for three counts of criminal sexual assault in Eaton County Circuit Court on February 5, 2018 in Charlotte, Michigan. (Photo by Scott Olson/Getty Images)

She said a former trainer, Debbie Van Horn, was charged with one count.

The charges stem from an investigation at the famed gymnastics training center run by Bela and Martha Karolyi north of Houston. Five former gymnasts implored authorities last month to determine whether the Karolyis could have prevented abuse at their since-closed gymnastics ranch. Two gymnasts said Nassar abused them there.

“There are no criminal charges against the Karolyis at this time. We don’t believe at this time there’s any corroborated evidence to support criminal charges,” Stroud said, adding that the Karolyis have been cooperative during the investigation.

But, she added, “It’s our belief that there was a total failure by (USA Gymnastics) to protect athletes.”

Nassar is serving decades in prison for sexual assault and possession of child pornography in Michigan, where hundreds of women and girls accused him of sexually abusing them under the guise of medical treatment, including while he worked for USA Gymnastics, which trains Olympians, and Michigan State University.

Texas Governor Greg Abbott ordered an investigation into what he called “gut-wrenching” allegations after the gymnasts came forward in Texas. The Texas Rangers are leading the Texas investigation, which also includes Walker County prosecutors and sheriff’s officials.

The Karolyis have denied knowledge of any mistreatment.

USA Gymnastics released a statement Friday afternoon on the latest charges saying it “supports and is fully cooperating with the investigations by the Texas Rangers, Congress and others, and we will continue to do so.”

Here is the complete statement:

astatement Larry Nassar Charged With Sex Assault In Texas

(© Copyright 2018 CBS Broadcasting Inc. All Rights Reserved. The Associated Press contributed to this report.)