Takeaways From Our Chinese Swimming Investigation

In the first days of 2021, seven months before the pandemic-delayed Tokyo Olympics, 23 of China’s best swimmers tested positive for the same banned drug at a domestic meet.

Chinese antidoping officials investigated and declared the case an unusual mass-contamination event that could be traced to the presence of a heart medication, trimetazidine, known as TMZ, in the kitchen of a hotel where the swimmers had stayed for a New Year’s event in late December 2020 and early January 2021.

The World Anti-Doping Agency, the global authority that oversees national drug-testing programs, looked into the episode but then accepted that theory and allowed China to keep the results secret.

All the while, the swimmers were allowed to continue racing, without suspensions or disqualifications. Some of the swimmers who provided positive samples went on to qualify for the Olympics, and to win medals — including three golds — for China. A few are favorites to win again at the Paris Olympics this year.

The incident would have remained in the shadows, a secret known only to a select few, had details of one of the most curious episodes in swimming not made their way out of the sealed files of the organizations trusted to keep sports fair.

Here are six takeaways from our report.

The Chinese-led investigation left key questions unanswered.

The global antidoping system works as an honor system. Major nations are charged with ensuring that their athletes are clean and must trust that others will do the same. So it was up to the Chinese doping regulator, known as Chinada, to investigate when 23 athletes tested positive for the same drug at the same domestic meet.

China assured global regulators that it had gone to unusual lengths to investigate. And yet, despite what was presented as a painstaking investigation involving scientists, China’s national police and even human test subjects, the Chinese did not provide answers to two fundamental questions: How did the TMZ get into their athletes’ systems? And how did the drug, a powerful prescription heart medication available only in pill form, get spread across various surfaces and containers in a kitchen in which food was prepared for some of China’s best athletes?

Global doping officials reacted differently with Russian figure skating sensation.

When Russia’s antidoping body cleared the teenage skater Kamila Valieva for testing positive for TMZ in 2022, WADA appealed its finding. It demanded that the Court of Arbitration for Sport, the authority that adjudicates disputes in global sports, reject Russia’s decision to clear Valieva, who was then still competing in the Winter Olympics in Beijing.

Valieva said she had been an unwitting victim of contamination, the same explanation that China provided for its swimmers. An appeal committee at Russia’s antidoping agency even accepted the claim that Valieva had tracked the source of the low concentration of the TMZ in her system to a strawberry dessert prepared for her by her grandfather, who said he had a prescription for the medication. The court summarily dismissed the claim as lacking credibility.

WADA took a far different stance in the case of the Chinese swimmers. Even though the Chinese had failed to find the source of the TMZ, WADA said it had “concluded that it was not in a position to disprove the possibility that contamination was the source of TMZ” and found no reason to appeal China’s decision to take no action.

Others who tested positive for similar drugs received at least provisional suspensions.

That the Chinese swimmers escaped even a short suspension is at odds with recent precedents and also the typical steps for handling questions about the validity of positive tests. Even Russia’s Valieva was provisionally barred from competition, at least for a few hours, before a Russian disciplinary board quickly reinstated her.

Last year, the United States Anti-Doping Agency suspended the vice president of international cycling’s governing body, the 45-year-old former Olympian Katerina Nash, after an out-of-competition test found a trace amount of a banned appetite stimulant in her system. Nash was later cleared, but only after she proved that she had been handling medication for a sick dog. TMZ is considered by antidoping regulators to be in the same category as that drug.

Antidoping experts dismissed a key claim made in the Chinese report.

The 61-page report that Chinese officials prepared to clear the 23 swimmers includes a claim that the low concentrations of TMZ found in all of the athletes’ samples was proof that they were not taking the substance to boost performances.

But experts consulted by The New York Times said that making such a blanket statement was incorrect, and that even if such low amounts would not be beneficial to a swimmer’s performance in the moment, they could just as easily suggest that the test was performed at the tail end of the excretion period for a larger dose of the drug.

WADA said the low concentrations, coupled with variances in testing results, factored into its decision not to act.

U.S. law enforcement is interested.

Federal investigators are aware of the episode and have taken some investigative steps to learn more.

It might seem odd that the F.B.I. or the Justice Department would have interest in the failed drug tests of swimmers from another nation in a competition that took place on the other side of the world. But a law passed in 2020 allows the American authorities to pursue drug cheats taking part in any international competition, wherever they may be. Critics of the law note that the statute does not apply to doping schemes in the biggest U.S. sports leagues, like the N.F.L., Major League Baseball or the N.B.A.

It was an awkward time to test positive.

At the time of the positive tests, the Chinese swimmers were fine-tuning their training as they geared up for the qualification meet for the Tokyo Olympics, which had been delayed a year because of the pandemic.

For the International Olympic Committee, a doping scandal involving the Chinese, a major force in world sport, would have been difficult to navigate at any time. But in the middle of 2021, only months before the opening of the Summer Games, it would have been a disaster. At the same time, China, battered by coronavirus and subject to some of the harshest lockdowns in the world, was continuing to push forward with plans to host the 2022 Winter Olympics in Beijing.