Roger Clemens has gone away from baseball, a once-certain Hall of Famer left as a pariah because of his link to anabolic steroids and human growth hormone.

His problems won't go away, however. The latest crisis is caused by a federal grand jury weighing an indictment for perjury.

As early as Tuesday, Assistant U.S. Attorney Daniel P. Butler will begin taking testimony from a cast of witnesses that may include Clemens' former trainer, Brian McNamee, and steroids supplier Kirk Radomski. It is not known if Clemens will be asked to appear.

Meeting in Washington, D.C., the grand jury likely will consider some physical evidence, including syringes held by McNamee that he claims contain Clemens' DNA. A grand jury allows prosecutors to take sworn testimony from witnesses and collect documents.

Clemens, named as one of at least 80 users of illegal performance-enhancing drugs in Major League Baseball's Mitchell report in 2007, has denied the charges. Hoping to clear his name, he appeared before a congressional committee in February. His testimony there conflicted with the statements of many others, including former teammate Andy Pettitte.

The grand jury will decide which version of the truth is more plausible. McNamee told investigators that during the 1998 season he injected Winstrol into Clemens' buttocks. He said he administered as many as 20 shots that season, when Clemens rewarded the Toronto Blue Jays with the fifth of his seven Cy Young Awards.

McNamee has said that in 2000, when he and Clemens worked for the Yankees, Clemens had moved on to other forms of testosterone: Deca-Durabolin and Sustanon 250. McNamee said he also gave him frequent injections of HGH, with the injections taking place at Clemens' apartment.

"We're very glad to hear a grand jury is convened, and we look forward to cooperating," McNamee's lawyer, Richard Emery, told the New York Daily News. "And we look forward to Brian being vindicated when the results are made public."

Clemens' Houston-based lawyer, Rusty Hardin, said he wasn't surprised the case had been passed to a grand jury.

"It is part of what a prosecutor does in the course of the investigation," he said.

Clemens, 46, won 354 games in a career that ended in 2007. He has sued McNamee for defamation. McNamee has threatened a countersuit in response.