By Ian Simpson
WASHINGTON (Reuters) - New York Yankees pitcher Andy Pettitte testified on Wednesday in Roger Clemens' federal perjury trial that there was a 50-50 chance he had misheard his friend and former teammate say he used human growth hormone.
In a second day of cross-examination by the defense, Pettitte said he might have misunderstood Clemens when the ace pitcher told him in 1999 or 2000 that he had used human growth hormone to recover from injury.
Years later, Clemens told Pettitte he had been referring to his wife Debbie's use of the drug during the conversation.
"As you sit here today, if you think about it in your own mind, it's 50-50. You might have heard it, or you might have misunderstood him. Is that fair?" defense attorney Mike Attanasio asked.
"I'd say that's fair," Pettitte said.
The admission prompted lawyers for Clemens to ask that Pettitte's testimony about the critical conversation be struck, since the pitcher cannot be sure of what he heard.
Pettitte's testimony is considered crucial to the government's case and having part of it struck - particularly his testimony about the HGH conversation with Clemens - would be considered a major blow to the prosecution.
Also Tuesday, Pettitte said he had not told Clemens about being injected with human growth hormone in 2002 and injecting himself with the drug in 2004, both times to deal with injuries.
Clemens was not present at the injections, Pettitte said shortly before his testimony wrapped up midmorning.
Clemens, 49, is being tried for a second time on federal charges of lying to the House of Representatives' Committee on Oversight and Government Reform about whether he used anabolic steroids and human growth hormone.
The panel was investigating drug use in Major League Baseball. Clemens, a seven-time winner of the Cy Young award, baseball's highest annual honor for a pitcher, is among the biggest baseball names linked to alleged drug use.
In a setback for the defense, U.S. District Judge Reggie Walton ruled that Clemens' lawyers could not touch on why his former trainer, Brian McNamee, had been let go by the Yankees in 2001.
McNamee left the Yankees after police investigating a Florida rape case said the trainer had lied to them. McNamee was never charged in the case.
After leaving the Yankees, McNamee continued to work with Clemens and Pettitte as a private trainer.
Walton said he had already ruled that the "nature of the underlying conduct is not admissible."
Although Pettitte had told congressional investigators that McNamee injected him with human growth hormone, the judge blocked similar testimony at the trial on Tuesday, ruling it could be prejudicial to Clemens' defense. Pettitte was allowed to testify that he received injections but did not say from whom.
Clemens first went on trial last July, but Walton declared a mistrial because prosecutors showed jurors a video clip that included material he had banned from the case unless it was raised by Clemens' defense team.
Pettitte has come out of retirement to bolster the Yankees' pitching staff and is playing his way back into shape with a Yankee farm club.
(Editing by Paul Thomasch, Mohammad Zargham and Eric Beech)