WASHINGTON - Roger Clemens' chief accuser has taken the stand in the former pitcher's perjury trial.

Brian McNamee has said he injected Clemens with steroids and human growth hormone in 1998, 2000 and 2001. Clemens is accused of lying to Congress in 2008 when he denied using those drugs.

McNamee, speaking softly in a thick New York accent, began his testimony Monday. The prosecution is starting its questioning of McNamee with biographical questions. The real drama is expected later, when he gets into his testimony against Clemens.

McNamee, Clemens' former strength coach, says he saved items that he used while injecting Clemens with performance-enhancing drugs. Prosecutors say they have evidence that some of the materials tested positive for the drugs as well as Clemens' DNA.