The retrial for seven-time Cy Young Award winner Roger Clemens begins Monday with jury selection as new questions emerge  about key evidence prosecutors intend to introduce at trial.

Clemens defense attorney Rusty Hardin said today at the final pretrial-motions hearing that he had serious questions about chain-of-custody issues over gauze pads and syringes that Clemens' former trainer, Brian McNamee, kept after allegedly injecting Clemens with human growth hormone.

Clemens was indicted in August 2010 on charges of obstruction of Congress, perjury and false statements as a result of testimony he gave to Congress regarding use of performance enhancing drugs, specifically steroids and human growth hormone, or HGH. Clemens is charged with making the false statements to congressional investigators in a Feb. 5, 2008, deposition. The perjury charges arose from his Feb. 13, 2008, testimony before the House Oversight and Government Reform Committee.

District Judge Reggie Walton declared a mistrial in the case in July after two days of testimony when prosecutors included portions of Clemens' February 2008 congressional testimony that referenced conversations former Yankee teammate Andy Pettitte had with his wife, Laura Pettitte, about the use of HGH. Walton had barred the prosecutors from referencing Pettitte's wife before the jury.

As the new trial approaches, Hardin is preparing to question the credibility of McNamee, the former Yankee trainer and the government's star witness in the case. Clemens' defense team is likely to raise questions about how McNamee kept the syringes and gauze pads he allegedly used to inject Clemens before providing them to government investigators.  During opening statements in the first trial, Hardin told the jury that McNamee "manufactured" the evidence.

At the hearing Friday, Hardin objected to a request by the prosecution to file a sealed secret document that would not be publicly available until later in the trial. The Justice Department prosecutors said they did not want the information to come out close to jury selection and that it would be released later.

"What the government has done, is two weeks before the trial listed eight things … that should not be in public," Hardin said. "This can be dealt with in jury selection.

"They are seeking to protect their key witness."

Hardin said that having the document be available to the public and the news media was fair to Clemens, who, he said, has "been unmercilessly beaten about" by the case that has dragged on for four years since his 2008 testimony before Congress. Hardin and a lawyer representing the Associated Press and the New York Times were unsuccessful in their request before Judge Walton, who decided to keep the document sealed, citing his need to have an impartial jury.

Hardin and Clemens' other defense lawyer,  Michael Attanasio, alluded during the hearing to the information's concerning an alleged sexual assault in October 2001 in which McNamee was involved. That case was still being resolved in a Florida court.

In an effort to bolster their case, two additional prosecutors from the Justice Department have joined the original three prosecutors who previously tried the case. Pettitte, who has returned to baseball this year after retiring, is expected to be a key prosecution witness.  He is expected to testify about his use of HGH in 2002 and 2004 and testify that Clemens told him he used HGH.

Hardin said at Friday's hearing that the government has carried out an additional 50 other interviews since the July mistrial. He complained to Judge Walton of an unfair advantage and that the "new information was gained through their own misconduct."

Walton told Hardin that the additional time was requested by the defense and that it was allowed equal time to prepare a defense.

Clemens has stated that the injections he received from McNamee were vitamin B12 and lidocaine.  The trial is expected to last six weeks. Opening arguments could begin next week after the jury of 12 people and four alternates is selected.