Prosecution concludes in Clemens trial, now in seventh week WASHINGTON (Reuters) - Government prosecutors accusing former pitching ace Roger Clemens of perjury wrapped up their case on Tuesday in a slow-moving criminal trial that has now entered its seventh week. Clemens' lawyers said they will need seven to eight days to make their case in defending the retired major league star against charges that he lied to a congressional panel when he denied using performance-enhancing drugs. Among the final witnesses federal prosecutors called to the stand on Tuesday was a former client of Brian McNamee, an ex-trainer of Clemens who says he injected Clemens with performance-enhancing drugs. Anthony Corso, a former Wall Street client of McNamee's, testified that McNamee told him that Clemens had used human growth hormone to recover more quickly from injuries and strains. Corso's testimony could bolster that of McNamee, whose allegations that he injected Clemens with steroids and human growth hormone have been the core of the government's case. "Mr McNamee had mentioned that Mr. Clemens was one of the athletes that he was getting positive results from him being able to push himself to limits ... using the medication to recover," Corso, 49, testified. Clemens' lawyers sought to cast doubt on Corso's testimony when the witness revealed he could not recall whether McNamee had mentioned Clemens during a conversation about saving syringes from players using the drugs. Corso testified that McNamee had told him in or around 2005 that the trainer had saved syringes from players to avoid getting "thrown under the bus" should the drug usage be discovered but said McNamee had not named Clemens as one of those players. According to prosecutors, Corso had told a grand jury in 2010 that McNamee claimed the syringes had been "used on Roger." The two answers are different. So would it be a fair testimony ... that you made a mistake? Clemens' lawyer Rusty Hardin asked. "Yes," Corso said. Clemens' attorneys have worked to paint McNamee as a liar who obtained immunity in exchange for his testimony. McNamee has said that he saved medical waste from a 2001 injection of anabolic steroids into Clemens and turned the evidence in to authorities in 2008. Prosecutors also called to the stand a toxicologist with the FBI who testified on the various forms of vitamin B-12. Clemens has claimed that McNamee injected him with vitamin B-12, not performance-enhancing drugs. Jury selection in this trial began April 16. Since the first days of testimony, two jurors have been dismissed for falling asleep, while the judge overseeing the case has warned lawyers about the slow pace. Another juror was let go because of a family death.