NEW YORK (CNN) -- Track star Marion Jones pleaded guilty Friday to lying to a federal investigator about taking banned substances.
"It is with a great amount of shame that I stand before you and tell you I have betrayed your trust," she said outside the courthouse Friday.
"Making these false statements to federal agents was an incredibly stupid thing for me to do, and I am responsible fully for my actions."
She asked for forgiveness, adding that she understood that a simple apology "might not be enough and sufficient to address the pain and the hurt I have caused you."
"Because of my actions, I am retiring from the sport of track and field, a sport which I deeply love," she said.
Further, Jones said the example of her "wrong choices and bad decisions" would "be used to make the lives of many people improve." Watch her tearful apology »
Jones -- who had long vehemently denied taking steroids -- appeared in U.S. District Court in White Plains, New York, before Judge Kenneth Karas.
Jones, 31, told the court that her then coach, Trevor Graham, first gave her steroids in 1999, telling her it was flaxseed oil.
She said she took the steroid known as "the clear," or THG, from that time until 2001, covering her participation in the 2000 Olympic Games in Sydney, Australia. See photos from throughout Jones' athletic career »
Graham has been indicted for allegedly lying to federal investigators. He has pleaded not guilty.
Federal sentencing guidelines suggest Jones could face jail time. She has been ordered back to court on January 11, 2008, for sentencing.
The admission could also cost her the five medals she won at the 2000 Olympic games in Sydney -- three of them gold.
Jones may not be the only one affected. Members of the entire 4x400m women's relay team could lose their gold medals as a result.
The admission could also have a ripple effect throughout the sports world, particularly for the investigation into alleged doping by other high-profile athletes. See athletes who have been stripped of honors »
Federal officials have been investigating BALCO, a laboratory linked to "the clear," which The Washington Post reported Jones admitted using. BALCO has been at the center of a long-running professional sports steroid scandal, including allegations against baseball home run king Barry Bonds.
The International Olympic Committee said the information Jones provides "may prove to be key" in advancing its inquiry into how the BALCO case may have "affected Olympic Games' competitions."
"Progress to date has been slow due to difficulties in gathering findings," the IOC said.
Jones filed a $25 million defamation lawsuit against Victor Conte, founder of BALCO, in 2004. The lawsuit accused him of trying to "destroy her career and reputation" when he said he had supplied her with performance-enhancing drugs.
That lawsuit was settled out of court for an undisclosed amount.
In 2005, Conte pleaded guilty to conspiracy and money laundering.
The charges against Jones were reported by the Post on Thursday, which quoted a letter written by Jones that acknowledged two federal counts against her.
Jones wrote a letter to family and friends telling them she would be making the plea, the Post reported.
The Post said it was read a copy of the letter, and that Jones' husband, when reached by the Post, did not dispute the contents.
"Red flags should have been raised when [Trevor Graham] told me not to tell anyone about" the supplement program, the Post quoted the letter as saying.
The Post said Jones noted in her letter that after taking the substance, she noticed changes in how she felt and how she was able to recover from workouts.
The Post said Graham had no comment.
The guilty plea by Jones contradicted years of public, often angry denials. The woman considered one of the greatest female athletes in the world has sworn she's never taken a banned substance. "I'm an athlete that has always been drug free," she has said.
Jones apologized in her letter, the Post reported. "I am sorry for disappointing you all in so many ways," she wrote. E-mail to a friend
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