Former elite cyclist Tammy Thomas pleaded not guilty in federal court Friday to charges of lying to a grand jury investigating steroid use in sports.

Thomas, 36, who is the first athlete indicted in a probe that has implicated some of the biggest names in track and professional baseball, was charged with three counts of perjury and one count of obstruction of justice.

Asked if she understood the charges, she told Magistrate Judge James Larson, "I do, your honor." Thomas, who appeared much slimmer than during her racing days, remained free on $50,000 bond.

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Defense attorney Tony Tamburello said outside court that Thomas is innocent of any crimes because she did not knowingly lie to the grand jury when she testified in October 2003.

Thomas was banned from cycling for life in August 2002 after the performance-enhancing drug Norbolethone was detected in her urine.

"She did not know at the time that she was taking that substance," Tamburello said. Nobody told her "this was Norbolethone."

The drug, once an obscure steroid used in human tests in the 1960s, was rediscovered by chemist Patrick Arnold, who supplied the Bay Area Laboratory Co-Operative with undetectable performance-enhancing drugs and is among five people who have pleaded guilty in the investigation.

Thomas, a Yazoo City, Miss. native, was a silver medalist in the individual sprint in the 2001 World Track Cycling Championships. She has maintained her innocence and said the positive results might have been triggered by contraceptives she used.

Seven people have been indicted in the probe of BALCO, a Burlingame supplement company that doled out steroids to elite athletes.

The indictment accuses Thomas of lying when she testified to a grand jury that she never used performance-enhancing drugs. She also is said to have lied when she testified that she did not get illegal drugs from Arnold, who was convicted in the scandal last year and sentenced to three months in prison.

"She never met Patrick Arnold," Tamburello said.

Each count against Thomas carries a maximum five-year term and $250,000 fine. She was ordered to appear March 23 in U.S. District Court, when a trial date is likely to be set.

Norbolethone was originally tested by Wyeth Laboratories in human trials during the 1960s as a potential treatment to help severely short people grow and for conditions causing weight loss. The company abandoned development of the steroid in the early 1970s and it was never marketed.

Arnold dusted off Wyeth's recipe and made new batches to boost athletic performance.

The United States Anti-Doping Agency wasn't testing for the steroid until a scientist determined Thomas had used the steroid.

The probe has netted guilty pleas from BALCO's founder Victor Conte, vice president James Valente and track coach Remi Korchemny. Also convicted was Greg Anderson, Barry Bonds' personal trainer, who served three months and is back in prison for refusing to testify against the Giants slugger.

Authorities suspect Bonds, like Thomas, lied to the 2003 grand jury when he said he never knowingly used steroids. An investigation of the San Francisco Giants slugger for perjury and possible tax-evasion charges is ongoing.

Trevor Graham, who coached track stars Marion Jones, Justin Gatlin and Tim Montgomery, has pleaded not guilty to charges of lying when he said he did not distribute steroids to his athletes or tell them where they could be obtained.

The case is United States v. Thomas, 06-0803.

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