It was an Indianapolis Star investigation in 2016 that publicly revealed the allegations against Dr. Nassar that had led to his firing by U.S.A. Gymnastics in 2015. In September of that year, a Star report detailed the experiences of a pair of gymnasts who said that they had been sexually abused. Rachael Denhollander was named in the initial report, and Jamie Dantzscher later revealed herself as the second gymnast.

Since those initial allegations, the case against Dr. Nassar has exploded. It now includes gymnasts at all levels, with at least eight having been members of the United States national team, five of whom have competed in the Olympics.

As the legal case against Dr. Nassar has expanded, there has been a great deal of criticism of U.S.A. Gymnastics as well, with several of the victims accusing the organization of either negligence or complicity in the abuse. In a lawsuit against U.S.A. Gymnastics, Ms. Maroney claimed the organization had paid her to sign a nondisclosure agreement that prevented her from speaking out about the abuse; the organization responded by saying she and her lawyer had initiated the process rather than the other way around. In March 2017, Steve Penny resigned as president of U.S.A. Gymnastics.

The decades-worth of allegations against Dr. Nassar will likely take some time to sort out, but Ms. Biles’s statement included a call for the investigation to continue until some sort of resolution can be found for the victims.

“We need to know why this was able to take place for so long and to so many of us,” she said. “We need to make sure something like this never happens again.”