WASHINGTON (CNN) -- The criminal trial of Vice President Dick Cheney's former chief of staff continues Tuesday with the playing of additional audio recordings from the secret grand jury questioning of Lewis "Scooter" Libby that led to his indictment.

Prosecutors are in their final days of laying out motive and evidence they believe will lead the jury to convict Libby of lying to save his job at the White House.

When Libby's defense team presents their case on Thursday, it will center on a theory their client was distracted by urgent national security matters if there are discrepancies in what he told investigators.

Libby has pleaded not guilty to a five-count indictment that includes allegations of perjury and obstruction of justice.

In the tapes the jury will hear Tuesday in his criminal trial, Libby told Special Counsel Patrick Fitzgerald on March 5, 2004 that he had trouble keeping track of the high volume of material on a given day.

"I can't possibly recall all the stuff I think is important, let alone other stuff that I don't think is as important," Libby said.

The quote, not yet played for the jury, is contained in a filing from Libby's lawyers Monday night. They are fighting an attempt by prosecutors to link the admission of certain evidence to whether he takes the stand.

Libby is accused of obstructing the FBI investigation into who leaked the identity of CIA agent Valerie Plame Wilson, whose husband, Joseph Wilson, wrote a July 2003 New York Times piece accusing the Bush administration of manipulating intelligence to justify the invasion of Iraq.