Former world indoor 200 metres champion Michelle Collins was suspended for eight years on Friday after being found guilty of doping charges in connection with the BALCO scandal.
Collins, 33, is the first athlete in the BALCO case to be suspended without a positive doping test or an admission of drug use.
The US Anti-Doping Agency (USADA) said a hearing panel of the American Arbitration Association (AAA)/North American Court of Arbitration for Sport (CAS) banned her after ruling that "USADA has proved, beyond a reasonable doubt, that Collins took EPO (erythropoietin), the testosterone/epitestosterone cream, and THG (tetrahydrogestrinone)."
Collins's suspension takes effect immediately. She forfeits all competitive results and winnings since February 1, 2002, the beginning of her violation, including her 200 metres world and U.S. indoor titles in 2003.
USADA added in a statement that Collins had "used these substances to enhance her performance" and elude the drug testers.
It said the panel found that Collins' "participation in the BALCO conspiracy amounted to a cover up and because her doping took place over an extended period it is appropriate to double the four years received by other BALCO athletes".
The Bay Area Laboratory Co-operative (BALCO) scandal erupted last year after Trevor Graham, ex-coach of world 100 metres record holder Tim Montgomery and Marion Jones, sent a syringe containing the previously undetectable designer steroid THG to USADA
BALCO laboratory head Victor Conte faces charges of distributing illegal performance-enhancing drugs to top sportsmen and women.
IAAF spokesman Nick Davies responded: "The IAAF believes that this judgement of eight years sends a strong message, namely that athletes who seek to cheat their fellow competitors and the public by engaging in doping processes specifically designed not to be detected will be brought to account....and they will be sanctioned even more severely than others."
Collins is considering an appeal to the Swiss-based Court of Arbitration for Sport (CAS).
"After a lengthy arbitration during which testimony from leading pharmacologists was presented, we are disappointed with the award," her attorney Brian Getz told Reuters via telephone from his San Francisco office.
The decision is a significant one for USADA and its policy of enforcing bans based on circumstantial evidence rather than failed doping tests.
"For the last year and a half, USADA has been committed to uncovering the truth regarding athletes and others who participated in the BALCO drug conspiracy," USADA chief executive officer Terry Madden said in a statement.
He said the ban backed its efforts "to protect the rights of the overwhelming majority of US athletes that compete drug-free".
Thirteen athletes have received sanctions for violations involving drugs associated with the BALCO conspiracy, USADA said.
The anti-doping agency is seeking lifetime bans for Montgomery and 1996 Olympic relay gold medallist Chryste Gaines. Multiple Olympic champion Jones, who Conte alleges to have been on drugs, maintains her innocence. She has never failed a dope test.
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