In any criminal or civil case, attorneys ask the opposition for information in a process commonly called "discovery."

What evidence is "discoverable" depends on the nature of the proceeding. In a criminal case, the government has a duty to a disclose all evidence that could exonerate the defendant, whether the other side asks for it or not.

However, Demjanjuk was not prosecuted as a criminal. His "trials" were denaturalization and extradition proceedings, which are considered civil rather than criminal.

"A denaturalization and extradition are deemed to be civil and not criminal [cases]," says Georgetown University Law School professor Sherman Lewis Cohn. "There are some people who argue that taking away a person's citizenship is close to criminal."

In a civil case, attorneys are required only to produce documents requested by the other side. Even evidence that is exculpatory need not be turned over if it is not requested.

However, Ryan says his personal policy has always been to hand over all exculpatory evidence, whether requested or not. He testified under oath last month he does not remember how or if he communicated that policy to his team of prosecutors on the case.

In any event, not complying with discovery requests is attorney misconduct. But bar associations and judges generally have been reluctant to punish lawyers unless their lack of compliance was intentional.

"The question is whether this is done knowingly--you may have a thorough search and not find anything exculpatory," says Cohn. "Certainly, if Mr. Ryan were involved in not carrying out discovery orders, he ought to be disciplined."

It is not clear, however, whether prosecutorial misconduct is enough to invalidate an entire prosecution. Over the years, the Supreme Court has generally left that decision in the hands of the judge.

Equally unclear is how Harvard might react to any ruling against Ryan, the University's most visible litigator.

In an interview shortly after she took office in November, General Counsel Margaret H. Marshall, Ryan's boss, said she was unfamiliar with Wiseman's investigation. She called a sanction of Ryan on the grounds of prosecutorial misconduct "such a hypothetical outcome that it would be irresponsible for me to comment."

Even as Ryan returned to his Holyoke Center office and Einhorn testified last week, a new wrinkle was added to the case.

Rep. James A. Traficant Jr. (D-Ohio), a longtime Demjanjuk supporter, said the real Ivan the Terrible was still alive in Eastern Europe and will soon be found. Traficant, who at one time admitted taking Mafia bribes as a county sheriff, offered no evidence for this claim.

Those involved in the case merely shrugged. It is only the latest allegation in a proceeding that only seems to grow more confusing--and to raise more questions.

Jim Newton of the Los Angeles Times contributed to this report.