Key witness in Clemens trial says mixed evidence WASHINGTON (Reuters) - The key witness in ex-baseball pitching ace Roger Clemens' perjury trial testified on Friday that evidence he turned over to federal authorities that allegedly showed Clemens had used performance-enhancing drugs also included items used by other players. With the defense questioning the credibility of the evidence, Brian McNamee, Clemens' former trainer, appeared to back away from his courtroom statements in more than 20 hours of testimony at U.S. District Court that the waste came only from drug use by Clemens, one of baseball's greatest pitchers. McNamee turned the medical waste from an alleged injection of anabolic steroids he gave to Clemens in August 2001 over to federal agents in January 2008 as evidence. The waste included needles, gauze, a broken steroid ampoule and human growth hormone stuffed into a Miller Lite beer can that was stored at McNamee's New York home. "Yes, sir," McNamee said when defense lawyer Rusty Hardin asked as part of cross-examination if all the waste from the beer can showed that Clemens had a steroid shot. Did the items involve only Clemens "and no one else?" Hardin asked. "I'm not sure about everyone else," McNamee said. He added: "I just know that there are other things in there that might have belonged to some other players." Asked how the other items that did not involve Clemens - a capped needle used in subcutaneous injections and vials of human growth hormone - got in the can, McNamee said: "Because I put them there." McNamee denied he was changing his testimony, saying he had told federal agents and congressional investigators that the evidence included items from other players. Prosecutors say scientists have linked Clemens' DNA and steroids to one of the syringes in the can. Friday's testimony continued Hardin's strategy of hammering McNamee over inconsistencies in his story. The evidence that McNamee turned over to investigators included packaged needles and steroid ampoules that McNamee said Clemens had given him when he was moving from his New York apartment in 2002. During that period, McNamee pleaded guilty to two driving under the influence charges in New York over a six-week period. Asked if that showed he had a drinking problem, McNamee said: "I disagree." The former trainer then gave a rambling explanation for one of the tickets. As he spoke, Hardin folded his arms, then walked over to the defense table, shuffled papers and returned to the lectern as McNamee kept talking. He won the Cy Young Award as best pitcher seven times and is among the biggest names implicated in drug use in baseball. To pick up the pace, Judge Reggie Walton imposed a 90-minute limit on questioning by prosecutors and by the defense. Testimony was scheduled to end on June 1 but Walton has moved back the expected termination date to June 8.