At least 368 gymnasts in the United States have alleged some form of sexual abuse over the past 20 years, a joint investigation by the Indianapolis Star and USA Today has revealed.

The nine-month investigation into police files and court documents found hundreds of cases of alleged sexual abuse by a total of 115 coaches and other adults they worked with, and systematic failures which enabled accused coaches to relocate to other gyms. Nearly all of the victims were girls.

“It’s just too easy for coaches to keep getting hired and hired and hired. Sexual abuse thrives on the fact that people are embarrassed about the topic, ashamed to talk about it, and they keep quiet about it,” Nancy Hogshead-Makar, CEO of the advocacy group Champion Women and a former Olympic swimmer, told the Star.

“And that’s exactly why molesting coaches keep getting hired at the next place. Nobody talks about a coach that is inappropriate with athletes; the coach quietly moves away and gets hired someplace else.”

The investigation found multiple such instances: coaches fired or forced to resign, in some cases ultimately convicted of sexual abuse, who retained their USA Gymnastics membership and were able to find employment in other certified gyms.

Former coach Jeffrey Bettman, who is serving a 25-year sentence in federal prison after pleading guilty to child pornography charges earlier this year, was found to have made 469 videos of 49 gymnasts he coached, all girls from eight to 16 years old, using secret cameras he placed in changing rooms in gyms in Oregon and California. Previously, Bettman had been fired from at least two other gyms for “creepy behavior” and faced charges in California on allegations of abusing a female gymnast, but was able to keep coaching at gyms approved by USA Gymnastics.

Another coach, William McCabe, was fired from two gyms in Florida before a 2006 guilty plea in Georgia to sexual exploitation of children, also for hiding camera in locker rooms. Ray Adams was fired or forced to resign from coaching positions at six gyms in four states, but subsequently hired by owners who believed his record was clean.

“We are saddened when any athlete has been harmed in the course of his or her gymnastics career,” USA Gymnastics said in a statement to the Star. “Nothing is more important to USA Gymnastics, the board of directors and CEO Steve Penny than protecting athletes, which requires sustained vigilance by everyone – coaches, athletes, parents, administrators and officials.”

The governing body said it had attempted to combat the problem by implementing criminal background checks, publishing the names of coaches banned from its competitions and providing educational materials to member gyms. But the Star countered that USA Gymnastics’ focus on educating members instead of setting ground rules and enforcing them has engendered an epidemic: the equivalent of one allegation every 20 days over the last two decades.

In September, the former team doctor for USA Gymnastics was accused of sexually assaulting two former gymnasts, including an Olympic medalist.

The civil suit filed in California alleged that Larry Nassar “systematically sexually groomed [the plaintiff, who was identified in court documents only as Jane Doe] and proceeded to repeatedly sexually abuse, harass and molest” her from 1994 to 2000, when she was a minor.

Shortly thereafter Nassar was fired from his position as a faculty member and treating clinician at Michigan State University after 16 more abuse complaints surfaced at the school.