Few athletes will be under as much scrutiny at the Paris Olympics as the swimmers from China.

Revelations that nearly two dozen elite Chinese swimmers tested positive for a banned substance ahead of the Tokyo Games — and were allowed to compete with no ramifications — have raised major concerns from the rest of the world about the seriousness of anti-doping efforts in a sport that has endured its share of scandals.

From the East German’s systematic, state-sponsored program of the 1970s and ’80s to a previous Chinese doping ring in the 1990s to questions over one-and-done Irish star Michelle Smith at the Atlanta Olympics to positive tests among Russian swimmers, this all feels familiar to those who’ve been paying attention to the pool for a while.

“There are cheaters all around the world. There’s no doubt in my mind,” said 1984 Olympic gold medalist Rowdy Gaines, now a commentator for NBC Sports. “When it becomes systemic, that’s a whole different issue.”

Prominent figures such as Katie Ledecky, winner of more individual swimming medals than any other female, and Michael Phelps, the most decorated Olympian ever with a staggering 23 gold medals, have both gone public with their complaints about a system that seems to have dropped the ball on a very clear-cut case.

“I have moved on to the next chapter in my life,” the now-retired Phelps said. “But it is imperative that we keep the book open for those who wish to be next.”

The World Anti-Doping Agency kept the book closed on 23 elite Chinese swimmers who tested positive for a banned heart medication ahead of the Tokyo Olympics in 2021. Five of those swimmers went on to win medals, including three golds.

The positive tests had been kept under wraps until they were reported in April by The New York Times and German broadcaster ARD. The Times further revealed that three of those swimmers had previously tested positive for another banned substance — again, with no ramifications.

WADA accepted the explanation of Chinese anti-doping officials that its athletes had ingested the banned substance through contaminated food at a hotel. World Aquatics, the governing body of swimming, went along with that decision.

“It should have been handled differently — for a matter of respect. Respect for the entire swimming and sports world,” Italian swimmer Nicolò Martinenghi said. “The situation needs to be fixed.”

With 11 swimmers who tested positive ahead of Tokyo set to compete again in Paris, criticism of the world’s anti-doping regulator only increased.

“If the international sports world continues to have its integrity impacted by the failures at WADA, the next generation isn’t going to be able to have the same belief that I once had in the system,” Phelps said during recent testimony before the U.S. Congress. “I urge you, the members of Congress, to engage in the fight against doping. We can uphold the values and fairness and integrity that are the cornerstone of Olympic and Paralympic sport.”

To that end, the U.S. has launched a criminal investigation into how the Chinese doping cases were handled. Brent Nowicki, the executive director of World Aquatics, has been subpoenaed to testify before Congress. World Aquatics said Monday that the Chinese swimmers going to Paris were undergoing increased drug testing of at least eight times this year before the Games.

But all of this comes too late to make it up to those who may have been cheated out of medals in Tokyo.

Take Ledecky, who swam a stellar anchor leg on the 4x200-meter freestyle relay to finish off a time that would’ve broken the previous world record, only to have a Chinese squad that included Zhang Yufei go even faster by four-tenths of a second to take both the gold and the world record. Zhang was among those who failed the pre-Olympic doping test.

Ledecky now knows what a swimmer like Shirley Babashoff, who was dubbed “Surly Shirley” for griping about the sudden rise of the East Germans at the 1976 Montreal Olympics, must’ve felt like — especially when her suspicions were proven to be correct.

“It’s tough to accept and ... feel what it’s like to be an athlete who won a (silver) medal behind some athletes who tested positive,” Ledecky told CBS. “I’ve seen it before with other athletes and always felt for those athletes.”

The doping revelations are sure to cast a pall over the swimming competition in Paris — especially if the Chinese have a strong performance.

They were fourth in the medal table in Tokyo with three golds and six medals overall, and they are coming off a stellar showing at the 2024 world championships in Doha, Qatar, with seven golds and a total of 11 medals. China trailed only the United States at that meet, though it must be noted that many top swimmers skipped the most recent worlds because of its unusual timing in an Olympic year.

“It’s disappointing to have this kind of distraction again around the Olympics,” said Tim Hinchey, the executive director of USA Swimming.

Then again, it’s nothing new for the sport.

“It’s happened time and time again,” Hinchey said. “So that’s disappointing.”

AP Sports Writer Andrew Dampf in Rome contributed.