Lance Armstrong has once again been accused of using banned performance-enhancing substances, this time by two former teammates. (Spencer Platt/GETTY IMAGES)

Lance Armstrong’s seven Tour de France titles could be jeopardized by the doping allegations made by two former cycling teammates even if Armstrong avoids a federal indictment or prosecution, according to people involved in the anti-doping movement and legal precedent.

The U.S. Anti-Doping Agency has already been in discussions with the attorney for Tyler Hamilton, who told the CBS News program “60 Minutes” that he received banned drugs from Armstrong and saw him using performance-enhancing drugs on a number of occasions.

USADA, which has a long history of prosecuting athletes who haven’t tested positive when other evidence becomes available, interviewed Floyd Landis when he became the first athlete to say publicly he witnessed drug use by Armstrong last May. After Landis made the allegations, the agency formally opened a wide-ranging investigation into doping in cycling.

“There is absolute historical precedent for USADA or [the World Anti-Doping Agency] to come in and adjudicate,” said Steven Ungerleider, an anti-doping expert with close ties to both agencies. “We have seen precedent where athletes have been stripped of their medals and earnings retroactively.”

The results can be dire for athletes found guilty of doping offenses, even if the rulings come years after the fact. If an athlete is found guilty of using banned drugs, all the results that occurred after that doping offense took place would be disqualified.

USADA chief executive Travis Tygart declined Monday to comment on the significance of Hamilton’s public statements but said in an e-mailed statement that “any anti-doping case initiated by USADA will be based on the actionable evidence obtained through a fair and thorough investigation.”

Armstrong, who has been under investigation by the U.S. Attorney’s Office in Los Angeles, has repeatedly denied ever using performance-enhancing drugs while attacking the credibility of his accusers. Both Landis and Hamilton tested positive for drugs and lied about their drug use for years before coming clean.

“Landis and Hamilton are simply not credible witnesses: They both lied about their own doping — and then made money by raising millions of dollars from friends in support of those lies,” Armstrong’s publicist Mark Fabiani said in an e-mail. “Now, when it has become potentially profitable, they’ve completely changed their stories.”

The World Anti-Doping Code places an eight-year statute of limitations on bringing doping charges, but one attorney said USADA would likely argue that the statute of limitations does not apply in a case involving fraud or concealment. Another countered that Armstrong’s first four Tour victories might be untouchable, with only the last three in jeopardy. Both attorneys declined to be identified because they did not wish to publicly comment on the case.

“I don’t think that issue has ever come up in a doping case,” one attorney said.

Hamilton alleged he witnessed Armstrong doping for three years beginning in 1999, when Armstrong won his first Tour de France; Landis claimed he witnessed doping between 2002 and ’04. Armstrong won seven straight Tour titles from 1999 to 2005.

USADA likely would wait until federal prosecutors abandon their probe or prosecute their case before bringing any charges against Armstrong or any U.S. cyclist.

USADA has previously brought doping cases against athletes who have retired if the evidence warrants it and the cases are significant. The lead agent in the Armstrong investigation, Food and Drug Administration Special Agent Jeff Novtizky, has testified in several USADA arbitrations, including one resolved just weeks ago in which a track and field agent received a 10-year ban from the sport.

Hamilton’s attorney, Chris Manderson, declined to say whether Hamilton was cooperating with USADA, but he said he had made “no deals” with USADA.

“Tyler is dedicated to telling the truth and helping to clean up the sport of cycling, so that young cyclists no longer have to face the Faustian bargain that he did,” Manderson said in an e-mail.

Late in 2008, Kayle Leogrande, a professional cyclist who had not tested positive for any drug, received a two-year doping ban and the disqualification of his results on the basis of testimony two alleged eyewitnesses gave to USADA.

Armstrong and his attorneys have made it clear they will attack the credibility of Landis and Hamilton in any proceeding; however, the standard of proof for doping cases is lower than the “reasonable doubt” standard for criminal cases. To find a person guilty of a doping offense, an arbitration panel must be “comfortably satisfied” that the evidence shows guilt.

The agency banned sprinter Marion Jones for two years in 2007, disqualifying all of her results from the time of the 2000 Summer Olympics, soon after she pleaded guilty to lying about her steroid use to federal investigators. Jones relinquished the five medals she had won at the 2000 Games in Sydney.

The “60 Minutes” report also claimed that Armstrong, his handlers and the world cycling governing body, UCI, jointly covered up a positive test in 2001 by Armstrong for erythropoietin (EPO). The report showed a letter written by USADA last month in which it sought information about the alleged coverup from the director of the Swiss lab that handled the case, and indicated that the director of that lab, Martial Saugy, had already met with USADA officials.

Saugy declined to comment from Lausanne, Switzerland, on Monday.

The Sunday report said former Armstrong teammate George Hincapie told the grand jury reviewing the case that he and Armstrong shared drugs with each other. Hincapie and his attorney have declined to discuss what Hincapie told the grand jury, citing the ongoing investigation.