American athlete Marion Jones displayed her five Olympic track and field medals in front of the Sydney Opera House in Australia on Oct. 1, 2000. Jones has acknowledged using steroids before the 2000 Summer Games in Sydney. Advertiser library photo

Jones, who won five medals at the Sydney Olympics, said she took the steroid known as "the clear" for two years beginning in 1999, according to the letter, which was read to The Washington Post by a person who had been given a copy of it. A person familiar with Jones's legal situation who requested anonymity confirmed the relevant facts that were described in the letter.

Jones said her former coach, Trevor Graham, gave her the substance, telling her it was the nutritional supplement flaxseed oil and said she should take it by putting two drops under her tongue. Graham, contacted by telephone today, said he had no comment.

Jones's admissions could cost her the three gold and two bronze medals she won in Sydney. In December 2004, the International Olympic Committee opened an investigation into allegations surrounding performance-enhancing drug use by Jones, once considered the greatest female athlete in the world.

In the past, Jones has vehemently denied using steroids or any performance-enhancing drugs.

Jones said she "trusted (Graham) and never thought for one second" she was using a performance-enhancing drug until after she left Graham's Raleigh, N.C.-based training camp at the end of 2002. "Red flags should have been raised when he told me not to tell anyone about" the supplement program, she said in the letter. She also said she noticed changes in how her body felt and how she was able to recover from workouts.

The clear, also known as THG, is a powerful steroid that was found to be at the center of the performance-enhancing drugs scandal known as Balco. More than a dozen track and field athletes have faced punishments for their use of the clear, which drug-testing authorities could not detect until Graham sent a sample of it to the U.S. Anti-Doping Agency in 2003.

Baseball players Gary Sheffield and Jason Giambi admitted during grand jury testimony to using the clear, according to the San Francisco Chronicle. Barry Bonds also admitted using a substance that he had been told by his personal trainer was flaxseed oil, the Chronicle reported.

The federal probe surrounding Balco, a nutritional supplements company based in Burliname, Calif., has resulted in five criminal convictions. Jones's coach, Graham, was indicted last November on three counts of lying to federal agents connected to the investigation. He has pled not guilty and his trial is scheduled for November.

The head of Balco, Victor Conte, has repeatedly and publicly accused Jones of using drugs.

Jones, who recently married former sprinter Obadele Thompson, said in her letter she planned to fly from her home in Austin, Texas, and meet her mother in New York to enter the plea. She said she faced up to six months in jail and would be sentenced in three months. Federal sentencing guidelines call for a maximum of five years in prison for one count of lying to federal agents.

"I want to apologize for all of this," she said, according to the person reading the letter, who spoke on condition of anonymity. "I am sorry for disappointing you all in so many ways."

Reached at their Austin home, Thompson declined comment on the letter, portions of which were read to him, saying "the process has to go through before you can make any comments ... I'm sure at the appropriate time, all necessary comments will be made." He did not dispute the contents of the letter.

When questioned in 2003 by federal agents investigating Balco, Jones said she lied about using the clear even though agents presented her with a sample of the substance and she immediately recognized it as what she had taken at Graham's behest, according to the letter. The letter said she lied because she panicked and wanted to protect herself and her coach.

Jones also said in the letter that she lied about a $25,000 check given to her by track athlete Tim Montgomery, the father of her young son, who pleaded guilty in New York this year for his part in a multimillion-dollar bank fraud and money-laundering scheme.

Jones said she told investigators she knew nothing about the deposit, even though Montgomery told her it was from the 2005 sale of a refurbished vehicle and was partial payment for $50,000 she had loaned him.