Double world champion Kelli White has been given a two-year suspension after admitting taking banned drugs.
White claims she took the stimulant to combat a tiredness disorder
The American sprinter tested positive for modafinil following her 100m victory at the 2003 World Championships in Paris.
White has also admitted taking undetectable steroids and EPO, according to the Reuters news agency.
The 27-year-old has been stripped of both her 100m and 200m gold medals from the Worlds.
"Ms White admits she used the substances to be as competitive as she could and several of the substances she used were undetectable," said a statement released on White's behalf.
"In doing this, I have not only cheated myself, but also my family, friends and sport. I am sorry for the poor choices I have made," she said.
White added: "The choice to co-operate is completely my own. I felt it was important to step up, accept responsibility and assist in cleaning up my sport.
"I anticipate other athletes will be charged but I really cannot say anything more at this time."
The statement added that the United States Anti-Doping Agency possessed "convincing" documentary evidence of her violations.
Her lawyer Jerrold D. Colton said in the statement: "Not only will Kelli be a witness in USADA'S proceedings as they go forward, but she is also a federal witness."
USADA said on Wednesday that White had accepted the minimum ban for her first offence involving the use of prohibited substances, including the blood-boosting erythropoietin.
The suspension started from Monday and means White will miss August's Olympic Games.
White hopes to have the ban reduced in exchange for help in cleaning up athletics.
"Ms White has made mistakes but I admire her courage in acknowledging these mistakes and accepting responsibility for them," said Terry Madden, USADA chief
"It is not easy to admit you have done wrong and then stand up to do something about it."
White is one of a host of American athletes caught up in the scandal surrounding the San Francisco laboratory Balco.
Coach Remi Korchemny has been strongly linked to Balco, which is also accused of distributing designer steroid THG.
White originally claimed to have taken modafinil to combat the sleep disorder narcolepsy.
She said she was prescribed it by Dr Brian Goldman, a psychiatrist who has worked with Balco president Victor Conte for almost 20 years.