Associated Press Writer

Roger Clemens' former personal trainer cooperated with investigators looking into steroids in baseball under threat of prosecution, an assistant U.S. attorney said in a court filing Thursday that could turn into a key factor in the lawsuit filed by the star pitcher.

In a declaration filed in federal court in Houston as part of Clemens' defamation lawsuit against Brian McNamee, assistant U.S. attorney Matthew Parrella said he told McNamee he was not a target of the investigation but could become one if he failed to cooperate.

If McNamee made any false statements to federal investigators or to the law firm hired by baseball to investigate drugs in the sport, Parrella said he could face prosecution.

McNamee told former Sen. George Mitchell's investigators that Clemens had used steroids and human growth hormone before baseball players and owners agreed to ban them.

"All arrangements, including time, date, and place, for the meetings were made by agents or assistant United States attorneys," Parrella said.

Also filed Thursday were declarations from attorney Charles Scheeler, who worked with Mitchell, and Earl Ward, an attorney for McNamee. Both supported McNamee's claim that he faced prosecution if he did not help investigators.

Clemens has filed a defamation lawsuit against McNamee, who was quoted in Mitchell's report as saying that he injected the seven-time Cy Young Award winner more than a dozen times with steroids and/or HGH in 1998, 2000 and 2001. Clemens repeatedly has denied using illegal performance-enhancing drugs.

McNamee's lawyers have argued that because he did not volunteer information about Clemens but was coerced into giving it under threat of prosecution, he is immune from any defamation.

"These documents definitely show that Brian was required, did not voluntarily, speak," Richard Emery, one of McNamee's lawyers, said. "This was all part of his proffer agreement and his cooperation agreement on pain of prosecution."

Lara Hollingsworth, one of Clemens' attorneys, said McNamee's conversations with Mitchell's people, a reporter and New York Yankees teammate Andy Pettitte were defamatory and not covered by any immunity provisions.

"These affidavits ... don't contradict our prior positions," Hollingsworth said. "(McNamee) was not under court order, he was not under legal compulsion. He talked to Senator Mitchell because it was to his benefit to do so."

Emery hopes most if not all of the case will be dismissed by U.S. District Judge Keith Ellison. Emery said the part of the suit dealing with an alleged conversation between McNamee and Pettitte in 2000 might remain as issue.

"There are no damages for Brian to talking to an admitted drug user about a mutual friend's drug use," Emery said. "It would lead to perhaps the deposition of Pettitte and Clemens, but that case is tiny."