LONDON – John Leonard is not backing down in his doping crusade.

The executive director of the American Swim Coaches Association , credentialed as a technical adviser through FINA – the governing body of all international swimming, including the 2012 Olympic Games – sparked a firestorm earlier this week. Leonard declared doubts about the world record 400-meter individual medley swim by Chinese teenager Ye Shiwen. Leonard, an American, basically said the gold-medal swim had all the earmarks of a drug-enhanced performance.

Leonard called Ye's performance "disturbing," and took particular aim at her incredible closing freestyle leg of 58.68 seconds, which he labeled "impossible." Since then he has been buffeted for what some sectors of the international swimming community consider an unfair attack on Ye's credibility.

But Leonard is not going to be muzzled, and he explained why in an interview Wednesday at the Aquatics Centre with Yahoo! Sports.

"If people don't speak out when they see something suspicious, the public is going to think nonsensical splits were real," Leonard said. "Then doping is going to have free reign for anything we don't know about right now.

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"It's an anomaly. Regardless where it comes from – take China's history completely out of it – an anomaly needs to be pointed out. And it's the only anomaly of the week."

The Florida-based Leonard has been around the sport for a long time – long enough to remember the doping scandals of the 1970s and '80s with the East Germans, and of the '90s with China. Americans also have had their share of positive drug tests over the years, not to mention whispers about others who swam dirty and were undetected.

Leonard said he doesn't want that dark history of the sport forgotten, for fear that it would have to be relived.

"There are a limited number of coaches left who have seen enough doped swimming to know what it looks like," he said.

Although some officials from USA Swimming have distanced themselves from Leonard's controversial comments, others in the American swimming community are glad he's speaking up.

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"The swimmers themselves can't say anything," said one former Olympian who is in London. "They'll just look bitter. But something needs to be said."

Enter Leonard, unrepentant. He believes Ye's swim was so outrageous that she was counseled to back way off in the closing 50 meters of her 200 IM victory three nights later. She swam that lap of freestyle in 29.32 seconds – slower than the last 50 of a race that was twice as long.

"She backed off, obviously," he said. "She never took a hard stroke at any point in time [in the final 50]. She was told to do what it takes to win, nice job – but if you look at tape from the 400 IM, it's two totally different swims.

"When she was coming from behind [against American Elizabeth Beisel] she held an eight-beat kick all the way through the 400. That's extremely tiring. In the 200 she used a simple, soft, six-beat kick to get home."

Ye also swam a leg in China's sixth-place 4x200 freestyle relay Wednesday night. Her final 100 split in that was 59.97 – also much slower than her closing leg of the more grueling 400 IM.

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