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Cyclist Tyler Hamilton has turned in his 2004 Olympic gold medal to the U.S. Anti-Doping Agency after admitting in a "60 Minutes" interview that he took performance enhancing drugs along with Lance Armstrong, and a second former teammate of Armstrong's also has come forward to accuse him of doping.

Hamilton's lawyer, Chris Manderson, tells the Wall Street Journal that the cyclist returned his medal because he didn't want the controversy to distract from his confession and allegations that he saw the seven-time Tour de France winner dope.

The USADA confirms it has Hamilton's medal and "will continue to work with the IOC and the USOC as appropriate concerning the final implications of our overall investigation," according to the Journal.

In the "60 Minutes" interview, Hamilton admitted that he doped and said Armstrong did, as well -- using the blood booster EPO in the 1999 Tour and before the race in 2000 and 2001. Armstrong's string of seven straight wins lasted from 1999-2005.

"I saw (EPO) in his refrigerator. ... I saw him inject it more than one time, like we all did. Like I did, many, many times," Hamilton said in the "60 Minutes" interview that was aired Thursday on the "CBS Evening News."

He said Armstrong "took what we all took ... the majority of the peloton," referring to riders in the race. "There was EPO ... testosterone ... a blood transfusion."

Armstrong immediately refuted the Hamilton interview, launching a website that denied the claims. He also tweeted: "20+ year career. 500 drug controls worldwide, in and out of competition. Never a failed test. I rest my case."

George Hincapie, a longtime member of Lance Armstrong's inner circle, also told federal authorities he saw the seven-time Tour de France winner use performance-enhancing drugs, according to another segment of the "60 Minutes" report that aired Friday night on the "CBS Evening News."

Hincapie has often been depicted as one of Armstrong's most loyal teammates and was with him for all seven Tour victories. In an interview last year, Armstrong said Hincapie was "like a brother to me."

Hincapie is among a number of former Armstrong teammates and employees who have appeared before a federal grand jury in Los Angeles investigating doping in cycling. Hamilton said he testified for six hours before the panel.

Last week, The Associated Press reported that a federal investigation into whether Armstrong and his former U.S. Postal team ran a systematic doping program is pushing into its second year, and that the feds recently asked French authorities for evidence in a request that mentions Armstrong by name.

As it did when Floyd Landis made his accusations, Armstrong's camp was quick to undercut the credibility of the accuser.

"Hamilton is actively seeking to make money by writing a book, and now he has completely changed the story he has always told before so that he could get himself on '60 Minutes' and increase his chances with publishers," Armstrong attorney Mark Fabiani said. "But greed and a hunger for publicity cannot change the facts: Lance Armstrong is the most tested athlete in the history of sports: He has passed nearly 500 tests over twenty years of competition."

A report by ESPN said Hamilton sent a letter to friends apologizing for lying about his past drug use. He said he testified six hours before the Los Angeles grand jury investigating Armstrong.

It will be up to the members of the grand jury to decide whether they believe the Hamilton who steadfastly denied doping for years -- at times concocting elaborate excuses for his positive tests -- or the one who testified under oath about the Armstrong case.

Landis, meanwhile, is an unlikely witness in this case, even though it was his revelations a year ago this week that poured fuel on the investigation.

He was stripped of his 2006 Tour de France title after testing positive for taking synthetic testosterone, denied taking performance-enhancing drugs for years, then finally admitted he doped for much of his career -- a mea culpa that also implicated Armstrong.

Asked to comment on Hamilton's interview, Landis said in an email to The AP: "The only comment I have is that I wish the best for Tyler."

Hamilton, 40, won a cycling gold medal at the 2004 Athens Games but failed a drug test later. He was allowed to keep his medal, however, because problems at a laboratory meant his backup 'B' sample could not be tested.

Months later, he was caught blood doping and served a two-year ban which ended in 2007.

Hamilton returned to racing and won the 2008 U.S. road championship, but retired last spring after admitting he took an antidepressant that contained the banned steroid DHEA. He was officially banned from cycling for eight years.

The "60 Minutes" segment, which will air in its entirety Sunday, also includes an interview with another former Armstrong teammate, Frankie Andreu.

Now one of the race directors at the Tour of California, Andreu told Pelley he took banned substances because lesser riders he believed were doping were passing him.

"Training alone wasn't doing it and I think that's how ... many of the other riders during that era felt, I mean, you kind of didn't have a choice," he is quoted as saying.

Andreu's wife, Betsy, who has said Armstrong discussed taking performance-enhancing drugs as doctors prepared him for cancer treatment in 1996, said she and her husband are working with investigators.

"We are cooperating, and we'll just tell the truth. And telling the truth has been costly," she said. "It's not popular to tell the truth about Lance."

Andreu and Hamilton were both in on the ground floor of Armstrong's record-breaking Tour de France domination, and were among the key cyclists he relied on and lived with as he put his grip on the three-week race.

They both rode with Armstrong for the first two Tours that he won, in 1999 and 2000, all together under U.S. Postal colors. Hamilton rode with Armstrong on his 2001 Tour win for U.S. Postal, too.

Andreu's Tour links with Armstrong also predate the start of his winning streak. Andreu and Armstrong were teamed together at Motorola for the 1993, '94, '95 and '96 Tours.

In his biography, "It's Not About the Bike," Armstrong described Andreu on that first winning Tour in 1999 as "a big powerful sprinter and our captain, an accomplished veteran who had known me since I was a teenager."

Hamilton was a climber, and one of his jobs was to help haul Armstrong up the Tour's punishing climbs.

But that teamwork is long gone, replaced by a damning accusation.

Also in the interview, Hamilton said Armstrong failed a drug test at the 2001 Tour de Suisse, the same accusation Landis made when he went public with his allegations last year.

The Associated Press contributed to this report.