The strange case of Wen Ho Lee has taken an even stranger turn. Federal prosecutors describe him as the worst atomic spy since the Rosenbergs. Yet he is charged only with improper handling of computer files when employed at the Los Alamos National Laboratory, something other government employees and officials, including a former director of the Central Intelligence Agency, have done without being seriously questioned.

The new twist came last week in a court hearing in Albuquerque, N.M., in which Mr. Lee’s lawyers are trying for the third time to get him released on bail pending trial in November. He has been held since December in a Santa Fe prison in virtual solitary confinement, most of the time in shackles.

An FBI witness admitted that he had misled the court last December by testifying that Mr. Lee had lied to a colleague in borrowing a computer to use in his improper downloading of files about nuclear weapons. Judge James Parker wrote at the time that he found Mr. Lee’s deceptions “deeply troubling” and denied bail.

But the FBI witness now acknowledges that he testified falsely that Mr. Lee told the colleague that he wanted merely to download a resume. A transcript of the FBI interrogation shows that the colleague never mentioned a resume. The FBI agent brushed off his false testimony as “an inadvertent error” and insisted that the scientist had been deceptive in other respects.

The agent had also testified in December that Mr. Lee had not disclosed certain contacts with Chinese scientists during an official visit to Beijing in the 1980s. But a report he filed after a 1986 trip listed seven Chinese scientists with whom he had spoken.

Mr. Lee’s lawyers also have brought out the fact that he easily passed polygraph examinations. He made high scores for credibility when denying that he had ever passed secrets or intended to harm the United States. This was when he felt threatened by a possible death penalty, since FBI interrogators had warned him that Julius and Ethel Rosenberg had been executed for not cooperating with the FBI.

The FBI has often relied heavily on the so-called lie detector, but in this case the agency disagrees with the way the tests were conducted and rejects the findings.

And then there were the Christmas cards. In December, the FBI agent testified that Mr. Lee had concealed his correspondence with Chinese scientists, saying he only had exchanged Christmas cards. But Mr. Lee’s lawyers last week produced a transcript of an FBI interview in which Lee discussed his correspondence with the Chinese scientists.

Whether or not Judge Parker allows bail, this latest hearing has shot holes in the government’s case against the scientist. And a request by the judge that the lawyers on both sides help him with a long list of related issues casts further doubt on the government’s case. For example, could Lee conceivably transfer the secret data to a hostile country? If so, would that harm the United States? How secret actually is this data from sophisticated foreign scientists? And what good would this mass of data do for an unsophisticated “rogue” country trying to make its first nuclear weapon?

How did a relatively minor mishandling of computer files develop into one of the greatest espionage cases in American history? Many East Asians think it was Mr. Lee’s birthplace and a fear of “yellow peril” that focused attention on him. And long before Mr. Lee was charged he became known as a dangerous atomic spy through news reports that grew out of a cooperative relationship between investigative reporters and prosecutors. Mr. Lee came close to being convicted in the press of espionage before he was even charged with a lesser crime.