Three-time Tour de France champion Greg LeMond has been served with a grand jury subpoena as part of a federal investigation of possible fraud and doping charges against Lance Armstrong and his associates, according to the New York Daily News.

The newspaper reported Friday that a grand jury in the U.S. District Court of the Central District of California issued the subpoena, which requests testimony and documents related to the four cycling teams Armstrong has led - U.S. Postal Service, Discovery Channel, Astana and RadioShack.

The letter also orders LeMond to appear at a federal courthouse in Los Angeles on July 30, according to the Daily News.

"We are overjoyed," LeMond's wife, Kathy, told the newspaper. "I hope the truth will come out."

The federal doping investigation was spurred by allegations made by American cyclist Floyd Landis in a series of e-mails sent to cycling and doping officials this spring. Landis, who was stripped of his 2006 Tour title for doping, said the use of banned substances was common on the U.S. Postal team when he rode with seven-time Tour winner Armstrong.

Tim Herman, Armstrong's attorney, told the Washington Post he was surprised the government would believe Landis, who has lied and under oath.

"What is so reprehensible is this guy bilked his best friends out of $2 million to fund a bogus defense," Herman said. "I can't believe anybody would want to take Floyd Landis to the prom."

Doug Miller, the lead prosecutor, refused to comment to The Associated Press.

Armstrong, who's currently 57th in the Tour, said Wednesday he had not been subpoenaed or contacted by lead investigator Jeff Novitzky, who uncovered the BALCO doping scandal.

"Like I said, as long as we have a legitimate and credible and fair investigation, we'll be happy to cooperate, but I'm not going to participate in any kind of witch hunt," Armstrong said.

He has repeatedly denied any involvement in doping and reiterated that position again.

"As long as I live I will deny that," he said. "There is absolutely no way I forced people, encouraged people, told people, helped people, facilitated ... Absolutely not. 100 percent."

Attorneys for former Armstrong teammates George Hincapie and Tyler Hamilton told the Washington Post Novitzky contacted them, but no meetings have occurred. Former Armstrong teammates Dave Zabriskie and Christian Vande Velde also have been contacted, the Post reported.