A retired medical doctor and friend of Floyd Landis is expanding his defence of the cyclist, contending a detailed analysis of documents shows the Tour de France champion did not have a positive drug test after all.

Dr. Arnie Baker made the case in a slideshow presentation Friday evening at the Tucson Convention Center, headquarters of the El Tour de Tucson race scheduled for Saturday.

Landis' agent Michael Henson said Landis was in Tucson to be the official starter for the race, but that the cyclist would not talk to reporters.

Landis, who denies doping, is contesting findings that showed two urine samples had elevated testosterone to epitestosterone levels during the Tour de France in July.

``There is no basis for a positive test in the first place,'' Baker said. ``How it got this far in the first place, I have no idea. But I've looked at the test, and to me, it's appalling.''

Speaking to an audience of about 100, most of them cyclists, Baker took several swipes at the French laboratory that analyzed Landis' urine samples. Displaying documents obtained from the U.S. Anti-Doping Agency by Landis' attorney Howard Jacobs, Baker said both urine samples, not just the backup ``B'' sample, were misidentified at various times during the lab's handling.

Earlier this week, World Anti-Doping Agency president and Montreal lawyer Dick Pound defended the French lab in a conference call, saying the case against the American cyclist should not be derailed by a mistake in the labelling of his backup urine specimen.

Travis Tygart, general counsel for USADA, did not return a telephone message left on his cell phone Friday night.

Baker said he has known Landis since 1997, when the cyclist took part in the Tucson event, his first pro race, as a tandem partner on Baker's team. The team won the race.

Baker, from San Diego, Calif., is retired from medical practice and is a full-time cycling coach.

He said he offered to take a look at the case after talking with Landis at the funeral for the cyclist's father-in-law, who committed suicide this summer.

``He hasn't asked me to do any of this,'' Baker said after his presentation, ``and I'm doing it pro bono.''

Baker also displayed a few of the internal documents that were ``leaked'' from the French lab to some news outlets and others. Baker denied that he had hacked into the lab's computer to get the documents, which are written in French, but said if they are authentic, they raise further questions about the lab's quality of work.

``I am not the hacker. These documents have been out there for more than a month,'' he said, adding that he had received them from more than one source.

Baker, who said he planned to place his presentation on his Web site arniecraigcycling.com., said authorities should be more concerned with what's in the documents than in who made them public.

Landis has asked that an arbitration hearing, expected to be held early next year, be open to the public. Landis can appeal that ruling to the international Court of Arbitration for Sport, which has the final say in such matters.

If found guilty of doping, Landis faces a minimum two-year ban from the sport and the loss of his Tour de France title.