Some key figures at Roger Clemens' trial, starting Monday, on charges that the former pitcher lied when he told Congress he never used steroids and human growth hormone:
— Clemens: The famed pitcher, who won a record seven Cy Young Awards, was adamant in his denials in 2008. Prosecutors maintain he lied and broke the law when he made those denials under oath to a congressional committee.
— Brian McNamee: The strength trainer who worked out with Clemens for a decade and helped mold the Rocket into one of the most feared power pitchers, even into his 40s. McNamee maintains he injected Clemens with steroids and human growth hormone — and saved the needles, which will be evidence at trial. He'll be the prosecution's most important witness.
— Andy Pettitte: The pitcher and former teammate of Clemens — with the New York Yankees and Houston Astros — is the only person besides McNamee who says Clemens acknowledged using drugs. Clemens has said his former friend is "a very honest fellow" but insists he "misremembers" their conversation, said to have taken place in 1999 or 2000.
— Kirk Radomski: The former batboy with the New York Mets was the primary source behind the 2007 Mitchell Report examining the use of performance-enhancing drugs in Major League Baseball. Radomski has admitted providing drugs to dozens of players, and McNamee says he got the drugs for Clemens from Radomski.
— U.S. District Judge Reggie Walton: The judge is a former athlete himself. He went to college on a football scholarship and revealed in a Clemens hearing last year that he and Ken Griffey Sr. grew up playing ball together in their hometown of Donora, Pa. Walton was appointed to the federal bench in 2001 by President George W. Bush after serving on the District of Columbia Superior Court and as an adviser for crime and drug policy to President George H.W. Bush. In declaring a mistrial last year, Walton blamed prosecutors for a mistake that a "first-year law student" wouldn't make. No stranger to high-profile cases, he presided over the trial of former Vice President Dick Cheney's onetime chief of staff, Scooter Libby.