LOS ANGELES -- A staff member of Lance Armstrong's Team RadioShack, who also has a past connection to Floyd Landis, arrived Wednesday morning to testify before a grand jury investigating allegations of doping and fraud in professional cycling, two people with knowledge of the probe told The Associated Press.
Allen Lim, an exercise physiologist whom Landis has said helped him cheat via the banned technique of blood doping, was called to appear before the panel convened in the U.S. District Court for the Central District of California, according to the sources who spoke on condition of anonymity Tuesday because the investigation was ongoing.
It was unclear how much time Lim spent before the panel, which broke for the day late Wednesday.
Lim would not confirm specifics of any grand jury appearance, but in a telephone call Tuesday night, he told ESPN.com's Bonnie D. Ford: "I am cooperating with the federal investigation and look forward to setting the record straight. When I worked with Floyd, I repeatedly told him that he didn't need to dope and should not dope, and I was absolutely not hired to help him to do so. Since then, I've spent my career promoting clean sport and keeping innumerable athletes from cheating, as well as assisting in catching those who are."
Lim is the latest witness in a probe that has featured some of cycling's biggest names, including Armstrong, who is a target of the investigation; Landis, who told authorities he participated in organized doping during the three years he rode for the U.S. Postal Service team; and triple Tour winner Greg LeMond, who in response to a subpoena turned over voluminous files related to civil litigation against Armstrong's longtime sponsor, the Trek Bicycle Co.
One of the people who spoke on condition of anonymity also told The Associated Press that former cyclist Kevin Livingston also has been subpoenaed and could testify before the grand jury as early as Wednesday. Livingston rode on Armstrong's Tour-winning teams in 1999 and 2000 and now works as a coach, operating out of the basement of an upscale bike shop in Austin that is co-owned by Armstrong.
Lim, a Ph.D. in exercise physiology who joined Team RadioShack for the 2010 season, has consistently denied the allegations by Landis, who also accused seven-time Tour winner Armstrong of doping.
"Floyd's admission speaks for itself," he told Ford last May. "The only thing I know with certainty is that I could not work with an athlete whom I knew to be using performance-enhancing drugs. I've worked very hard to make this a better sport."
Landis told Ford a different account last spring, saying that he paid Lim $80,000 during the 2005 season, chiefly for helping with the logistics of transporting bags of Landis' own blood to be transfused. The method, known as blood doping, increases an endurance athlete's ability to process oxygen.
Lim vehemently denied the arrangement and said Landis paid him a fraction of that amount for training advice only.
"The thing is, he really didn't know anything about the doping, and by that time, I had learned it all," Landis told Ford during a lengthy interview last May, his first public admission that he had lied for the previous four years about doping during his career.
"I just needed somebody around that was smart and educated and I could trust, with dealing with logistics. I originally hired him to be an assistant and be around when I was training and drive a car behind me. ... Eventually he did help me with the other stuff. But it was more my own knowledge that I used to do that, it wasn't any advice I got from him. He just happened to help because it was there."
Lim attended the 2006 Tour de France but did not work formally for Landis that season. Landis told Ford that Lim would have had no direct knowledge of his doping activities during that time.
Landis won the Tour in 2006 but was stripped of his title after testing positive for synthetic testosterone. He fought to have the test results reversed through two rounds of arbitration but was unsuccessful and served a two-year suspension, returning to race on the U.S. domestic circuit last year. He is currently without a team.
Lim subsequently joined the Slipstream organization when it was still a developmental team. He remained with the team -- managed by Jonathan Vaughters, a former Postal rider who was vocal about creating an environment where young American riders would not feel pressure to dope -- through last season, when the organization now known as Garmin-Transitions achieved elite Pro Tour status.
In the fall of 2007, Lim told Ford he had been stung by what he said were false accusations that he must have known Landis was cheating when he won the Tour, and said he hoped to "get this demon off my back."
"I will not comment on his guilt or innocence," Lim told Ford at that time. "I'm not so naïve as to think that no one takes drugs, but I'm also not so cynical as to think that everyone's taking drugs. If he did dope, then he's one helluva conflicted individual, because if there's anyone who understands the distinction between right and wrong, it's Floyd."
Lim defected to RadioShack this season in order to have a chance to work with Armstrong and young talent Taylor Phinney, whom Lim advised throughout Phinney's teenage years in Boulder, Colo. where both men live. Phinney won the Under-23 world championship time trial gold medal Wednesday in Australia.
Armstrong became a more important figure in the probe this spring after Landis dropped long-standing denials and admitted he used performance-enhancing drugs. In doing so, he accused Armstrong and others of systematic drug use.
Landis initially made his accusations in e-mails, and Lim was mentioned.
Armstrong has vehemently denied the accusations, and his attorney has described Landis as a "serial liar."
Thom Mrozek, a spokesman for the U.S. Attorney's Office in Los Angeles, declined comment when asked about whether Lim was appearing before the grand jury.
Last week, Stephanie McIlvain, a longtime Armstrong friend, spent a day testifying before the grand jury. Her attorney later said McIlvain told the panel she had never heard Armstrong admit that he used banned substances.
McIlvain was present in the hospital room where Armstrong was being treated for cancer in 1996, when former teammate Frankie Andreu and his wife, Betsy, claim the cyclist told doctors he used performance-enhancing drugs.
Armstrong has denied that he cheated -- or that he made such a statement -- and McIlvain has previously testified in a civil case that she didn't hear Armstrong admit to doping in that conversation.
Information from ESPN.com's Bonnie D. Ford and The Associated Press was used in this report.