However, Landis is "certain he hasn't ingested any prohibited substance," said lawyer Jose Maria Buxeda. "He knows there is a natural explanation to the (initial) finding.

"He's pretty sure we will be able to prove, if this result is confirmed, that it is due to natural causes, to a natural reaction of his body, either (normally) or in the circumstances he was in that particular stage."

The result of the "B" sample test will not be available before Saturday, Buxeda told The Associated Press outside the French lab conducting the analysis.

But the process of determining whether the American cyclist is guilty of doping or whether his body naturally produced the higher than normal testosterone levels could take six months to a year, the Spanish attorney said.

Buxeda and another lawyer, Luis Sanz, were present for the start of the testing. Landis, a native of Lancaster County, Pa., was in the United States.

"The reason why Mr. Sanz and myself said that probably the result is going to be the same is because statistically the results of the `B' sample usually _ not always _ but usually confirm the results of the `A' sample," said Buxeda, speaking in English.

Landis showed a testosterone imbalance in an initial urine sample taken during the Tour de France. Both "A" and "B" samples were provided July 20 after he sped his way back into contention after winning the tough Stage 17 of the three-week Tour.

Michael Henson, a spokesman for Landis, confirmed Tuesday that the July 20 urine test turned up an 11:1 testosterone/epitestosterone ratio _ far above the 4:1 limit allowed.

He acknowledged Wednesday that a carbon isotope ratio test, which detects synthetic testosterone, had been done on the "A" sample. He would not divulge the result, but the New York Times has reported that Landis' personal doctor, Brent Kay, confirmed the sample tested positive for synthetic testosterone.

On Thursday, Buxeda contended that even lab results that show the banned substance was synthetic, introduced from an outside source, would only be a "presumption" _ not a certainty.

"I wouldn't say that they (lab experts) know," Buxeda said. "I would say they can presume. They do not have the certainty. ... It is only a presumption."

David Cowan, director of the Drug Control Center at King's College in London, said the carbon isotope ratio test "is the most definitive measure we have at this time."

"If there is a synthetic found (in the sample) than any defense is difficult to prove," he said.

Buxeda suggested Landis' positive result could have been produced by a combination of "dehydration, maximum effort. It's been said alcohol."

"We have to study all these factors," he said, referring to Landis' comments that he and teammates drank beer and whiskey after stage 16.

Landis has said he would undergo further tests to prove his body's natural metabolism _ not doping _ caused the elevated result.

If the "B" sample is positive, the results will be sent to the U.S. Anti-Doping Agency, which would handle the case. If found guilty, Landis would be stripped of the Tour de France title and banned for two years.

"The process could be six, eight months till one year," said Buxeda, who represented Spanish cyclist Roberto Heras when he was suspended for two years after testing positive for EPO.

"Of course, if it doesn't confirm the `A; sample, the case is closed," Buxeda said. Under UCI rules, a negative `B' sample is accepted as the definitive response and the positive `A' sample is ignored.

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Associated Press writer Paul Logothetis in London contributed to this report. blog comments powered by Disqus