Raisman, 23, told CBS' 60 Minutes in an interview airing Sunday that Nassar first treated her when she was 15. She says she spoke to FBI investigators about Nassar after the 2016 Summer Games in Rio.
More than 125 women have alleged abuse by Nassar, who is in jail awaiting sentencing on child pornography charges and a trial on charges of sexual misconduct. Plaintiffs are also suing USA Gymnastics, the U.S. Olympic Committee and Michigan State University, where Nassar was a doctor and faculty member.
Raisman said people have asked her why more of Nassar's accusers didn't lodge complaints about him earlier.
"Why are we looking at why didn't the girls speak up?" she says. "Why not look at what about the culture? What did USA Gymnastics do, and Larry Nassar do, to manipulate these girls so much that they are so afraid to speak up?"