Jurors hearing evidence in Arthur Andersen LLP's obstruction of justice trial have yet to hear from the man who pleaded guilty to leading the firm's destruction of Enron-related documents.

Former Andersen partner David B. Duncan, 43, is expected this week to break his public silence on the mass shredding of documents and deleting of computer records. The destruction of Enron audit material last year came as the Securities and Exchange Commission began probing the energy company's complicated finances.

Prosecutors have consistently refused to say whom they will question or when.

Rusty Hardin, Andersen's lawyer, said he expected Duncan's testimony on Tuesday or later.

"We don't know what he's going to say," Hardin added.

When Duncan pleaded guilty to obstruction April 9, he described how he ordered Andersen employees to comply with a policy to retain certain documents and destroy others on Oct. 21, two days after he learned that the SEC was investigating the company.

"I also personally destroyed such documents," he told U.S. District Judge Melinda Harmon. "I accept that my conduct violated federal law."

Duncan has so far been publicly silent about Andersen and Enron. He invoked his Fifth Amendment right against self-incrimination before Congress in January and at a deposition for shareholder lawsuits in February.

Experts said cases of both the prosecution and defense could rest on what jurors think of Duncan.

"Duncan is clearly the franchise player in the government's lineup," said Robert Mintz, a former federal prosecutor and now a partner at McCarter & English in Newark, N.J. "He will lay out each phase of the crime."

Hardin could use the plea agreement to discredit Duncan, said Jeffrey Parsons, a veteran defense attorney in antitrust, business fraud and oil and gas securities cases for Beirne, Maynard & Parsons in Houston.

Duncan's sentencing is Aug. 26, and government recommendations that his punishment be more lenient than the maximum 10-year prison term could turn on whether prosecutors believe he has cooperated sufficiently with them, Parsons said.

"If Rusty wants to use that weapon, he can try to show Duncan is biased toward the prosecution just from the standpoint that he doesn't want to cross them," Parsons said.

Duncan was Andersen's lead partner on Enron's account, heading a staff of about 100 workers auditing the high-profile client's books. He was fired in January, shortly after Andersen publicly acknowledged the shredding.