The U.S. Justice Department has opened a criminal probe into a sports doping scandal involving nearly two dozen elite Chinese swimmers.

The Justice Department rarely comments on ongoing investigations, but two international sports organizations have confirmed to NPR that a criminal probe is underway.

In May, a bipartisan group of U.S. lawmakers called for an investigation. “It is imperative to assess whether these alleged doping practices were state-sponsored,” they said in a statement.

Justice Department officials didn’t respond to NPR’s request for comment, but one focus of the probe appears to be on the World Anti-Doping Agency, known as WADA. The agency reviewed repeated positive tests for two banned substances by some elite Chinese swimmers over a period of years. But it kept results of the tests secret, and the athletes were allowed to compete in 2021 at the Tokyo Summer Games.

Chinese swimmers will compete in Paris

Eleven of those Chinese athletes have now qualified for China’s national team and are expected once again to swim head-to-head against U.S. athletes at the Paris Olympics.

World Aquatics, which governs international swimming competitions, said in a statement to NPR that its executive director, Brent Nowicki, has been subpoenaed “by the United States government” to testify in the case. “He is working to schedule a meeting with the government, which, in all likelihood will obviate the need for testimony before a grand jury,” said the World Aquatics statement.

WADA also issued a statement saying it handled the Chinese drug tests properly and was “disappointed” by the probe.

The organization, headquartered in Montreal, Canada, accused U.S. officials of exceeding their authority in the case. “The United States purports to exercise extraterritorial criminal jurisdiction over participants in the global anti-doping system,” said WADA’s statement.

News of the positive test results first became public in April of this year.

The revelations sparked international condemnation of WADA, Chinese authorities and their decision to keep the doping cases under wraps.

‘People are just getting away with everything’

WADA, meanwhile, says it chose to accept the Chinese government’s explanation that repeated positive tests for performance enhancing drugs by top swimmers were the result of accidental contamination.

U.S. drug testing experts and many American athletes have rejected those explanations.

Testifying last month before a U.S. House committee, Olympic gold medalist Michael Phelps called for major reforms to the international system designed to catch athletes who use drugs to cheat. “Right now people are just getting away with everything,” Phelps said. “How is that possible? It makes no sense.”

Travis Tygart, head of the United States Anti-Doping Agency, which monitors and penalizes American athletes if they cheat, testified that WADA has failed for years to properly punish Chinese and also Russian sports teams that regularly use performance-enhancing drugs.

“Russia and China have been too big to fail in [WADA’s] eyes and they get a different set of rules than the rest of the world does unfortunately,” Tygart said.