Olympian McKayla Maroney says former USA Gymnastics doctor Larry Nassar molested her hundreds of times, starting from the first day he examined her.
In January, the 54-year-old was sentenced to 40 to 175 years in prison for sexually abusing young female gymnasts, including Maroney and fellow "Fierce Five" members Aly Raisman and Jordyn Wieber, under the guise of medical treatment.
In an exclusive interview with NBC News' Savannah Guthrie for a special investigative edition of Dateline, Maroney, 22, said she first met Nassar at the USA Gymnastics National Team Training Center at Karolyi Ranch in Texas when she was 13.
"He told me he was going to do like a checkup on me and that was the first day that I was abused," she said.
Maroney said Nassar molested her "every time" she met with him after that first meeting, and hundreds of times before she quit competitive gymnastics in 2016.
"He said that nobody would understand this and the sacrifice that it takes to get to the Olympics, so you can't tell people this," she said. "He didn't say it in a way that was like, mean, or anything like that. I actually was like, 'That makes sense. I don't want to tell anybody about this.' I didn't believe that they would understand."
More than 250 women and girls, as well as a male gymnast, have accused Nassar of sexual abuse. Among them are a fourth "Fierce Five" member, Gabby Douglas, and Simone Biles, who won gold medals at the 2016 Summer Olympics.
Raisman, Wieber and other accusers had appeared in court in person during Nassar's sentencing hearing to confront him with victim-impact statements. Maroney had her statement read in court on her behalf.
"Dr. Nassar told me that I was receiving 'medically necessary treatment that he had been performing on patients for over 30 years,'" her statement said. "As it turns out, much to my demise, Dr Nassar was not a doctor, he in fact was, and forever shall be, a child molester, and a monster of a human being. End of story! He abused my trust, he abused my body and he left scars on my psyche that may never go away."
"It is time to hold the leadership of Michigan State University, USA Gymnastics and the United States Olympic Committee accountable for allowing, and in some cases enabling, his crimes," she wrote. "Our silence has given the wrong people power for too long, and it's time to take our power back."
Maroney said at a charity luncheon on Tuesday that USA Gymnastics, the U.S. Olympic Committee and Michigan State University, where Nassar had a sports medicine practice, only "cared about is money and medals," adding, "It didn't seem they cared about anything else."
"We are doing everything possible to prevent abuse, and we hope everything we do going forward makes this very clear," USA Gymnastics said in a statement to Dateline.
The USOC had previously apologized to Nassar's victims and called for reforms and Michigan State University has said it's making changes in response to criticism it ignored warnings that the former doctor was a predator, NBC News said.
On Tuesday, Wieber filed a lawsuit against USA Gymnastics and Michigan State University, claiming that they "failed to disclose and hid" Nassar's criminal conduct from the public and law enforcement "by virtue of defendants conspiratorial and fraudulent conduct" and allowed him "to remain in a position of influence and his unsupervised or negligently supervised conduct with minor participants and members made the molestation and abuse of minor participants possible."
"He was the only male allowed to be present in the athlete dorm rooms to do whatever he wanted," Wieber wrote. "He was allowed to treat us in hotel rooms alone and without any supervision. Nobody was protecting us from being taken advantage of. Nobody was even concerned whether or not we were being sexually abused. I was not protected. My teammates were not protected."
In February, Nassar was sentenced to another 40 to 125 years in prison for felony criminal sexual conduct in the first degree. He was also sentenced to 60 years in prison in December for child pornography charges.
The special edition to Dateline airs Sunday night at 7 p.m. ET / 6 p.m. CT.
(E! and NBC News are part of the NBCUniversal family.)