Former Major League baseball pitcher Roger Clemens' former trainer Brian...

Former Major League baseball pitcher Roger Clemens' former trainer Brian McNamee leaves federal court in Washington on May 16, 2012. Credit: AP

WASHINGTON -- Brian McNamee, the government's star witness in the Roger Clemens perjury trial, admitted under defense questioning Thursday that he lied repeatedly to federal and professional baseball steroid investigators when they asked him about Clemens and others.

Pressed by Clemens' attorney, Rusty Hardin, on the most contentious day of the trial yet, McNamee admitted he lied about the number of times he gave shots to Clemens and whether he had any physical evidence to prove it.

But while conceding he initially had sought to downplay Clemens' steroid use in those meetings -- "It's not like I didn't say the truth, I just minimized it," McNamee said at one point -- he did not back away from his accusation that Clemens used steroids and human growth hormone.

"I never lied about the usage. Never. Just the amounts," McNamee said.

He admitted he initially said he gave Clemens four shots in 1998, but the real number was more like six to 10.

In the daylong cross-examination, interrupted often by prosecution objections, Hardin accused McNamee of telling federal prosecutors what they wanted to hear about Clemens' drug use. He also pointed out that McNamee had gotten a "free pass" from being prosecuted for distributing steroids by testifying against his former client.

McNamee insisted he told the truth. "I might get locked up for lying," he said.

But Hardin grilled McNamee on inconsistencies, gaps and changes in stories he initially told investigators and later revised as he testified to Congress and the grand jury that indicted Clemens.

Hardin asked McNamee if in 2007 he had continued to urge Clemens to use him as a trainer and to ask for favors such as baseball tickets "at the very time you're selling him down the river," but not telling Clemens about the secret meetings with federal authorities.

McNamee said federal prosecutors instructed him not to tell anyone about their meetings.

Hardin said McNamee also changed his story about why he initially lied to federal investigators about having saved in August 2001 needles, cotton balls and gauze from a steroid shot to Clemens, and then later produced the materials in January 2008.

Investigators "read the riot act" to McNamee and told him to "stop lying," Hardin said.

"Yes, you're right, it's a moving target," McNamee said about the "evolving" stories he has given for saving the medical waste.

"All that lying and not one blankety-blank thing has happened to you," Hardin said, noting McNamee said he reluctantly told "the truth" about Clemens to avoid going to jail.

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