Richard Krajcik, deputy director of the nuclear weapons division at Los Alamos National Laboratory, testified at Lee's bond hearing that Lee came to see him in his office after the polygraph, which Lee took before he was fired from the lab March 8.
"He indicated that he did not intentionally pass on information to a foreign country," Krajcik said under questioning by a federal prosecutor. "He said he may have accidentally passed on information to a foreign country."
The Taiwanese-born Lee, 60, a naturalized U.S. citizen, has pleaded innocent to charges that he downloaded U.S. nuclear secrets and transferred them to unsecure computers. He is appealing a federal magistrate's decision that he be held without bond. Lee isn't accused of spying or passing any nuclear secrets
Krajcik said the FBI polygraph was about the W-88, the smallest and most sophisticated warhead in the U.S. nuclear arsenal.
Krajcik said the two questions Lee failed were: whether he had passed information to a foreign country and whether he had passed classified codes to a foreign country. Krajcik didn't give the date of the polygraph.
In addition to the meeting with Lee in his office, Krajcik said he was present when Lee was interviewed by the FBI on March 5 and that he appeared "deceptive and evasive."
"My reaction was that Mr. Lee was not being candid and truthful in his response to the questions," Krajcik said.
U.S. District Judge James Parker, who is hearing the bond request, asked Krajcik: "Why is he (Lee) such a danger now if he has not been since 1994?"
"Because he has information due to his experience that he can pass on," Krajcik replied.
The government has said that Lee for years was under suspicion of being a spy for China and that he allegedly downloaded most of the nuclear information in 1993-94. He wasn't fired until March 8 of this year.
First Assistant U.S. Attorney Robert Gorence said Lee should not be released because he could act as a "consultant" to anybody who wanted to use the information. He said Lee may be able to give the information to a "customer."
Friends and colleagues have defended Lee, saying many people handled data without being aware of security concerns. They also have suggested he is being singled out because of his ethnicity. A handful of Lee supporters showed up again today outside the courthouse, chanting slogans and holding signs in his defense.
Prosecutors have used expert testimony to paint Lee as a man who was trying to steal a battery of files that could be used to design and test a variety of nuclear weapons. They said he should be held in jail with supervised visits pending his trial.
On Monday, Krajcik testified: "When I first realized what was downloaded, I realized I was looking at a chilling collection of codes and files."
Krajcik said the files contained physical measurements and the codes and databases needed to design and conduct virtual tests on a "range of weapons."
Krajcik said some of the files Lee downloaded were related to his job as a code writer, but many weren't.
Modern nuclear weapons are developed in two stages, Krajcik testified. Gorence asked Krajcik after discussions of each stage how much of the code Lee had downloaded. On the secondary stage, Krajcik responded, "That (set of) codes was taken in its entirety and it was the very latest we had."
Krajcik also said he noticed one code was missing in the primary stage. He said he asked other scientists who were working on that code if Lee had approached them.
"They indicated to me that Lee had tried to procure a copy of that code, but he was unsuccessful," Krajcik said, adding that Lee made three attempts. Krajcik said Lee dropped the matter when he was questioned about his interest.
Lee's attorneys, who had yet to cross-examine Krajcik, said Monday that Lee didn't act like a spy.
Lee made no effort to conceal his activity or disguise the files' contents, and he knew computers were keeping logs of everything he did, attorney John Cline said.
Cheryl L. Wampler, a laboratory security expert, testified Monday that it took a concerted effort on Lee's part to bypass security to collect the files he is accused of downloading to unsecure computers and portable computer tapes.
Wampler also said Lee transmitted unclassified information to foreign countries that revealed two of his lab computer logins and passwords, which could be viewed by computer hackers.
And, in 1993, a security program that looks for suspicious activity flagged Lee for moving information from secure areas to unsecure areas. Wampler testified that the woman whose job it is to review such flags incorrectly decided the actions were a necessary part of the changeover to a new computer system and decided to ignore the warning.
It took Lee 40 hours over several months in 1993 and 1994 to download the files, which he declassified by putting in areas that could be reached by lab employees without security clearance and computer hackers, Wampler said.
"The files were open to not very sophisticated hackers on the Internet," she said.
The hearing is on the defense appeal of a magistrate's order denying $100,000 bail for Lee. He faces life in prison if convicted.
Parker is expected to decide whether to grant bail later in the week.
U.S. Magistrate Don Svet ruled Dec. 13 that freeing Lee until his trial would pose a "clear and present danger to the national security of the United States."
Lee is charged with 59 counts under the Atomic Energy and Espionage Ats. The charges allege transfer of classified material from secure to unsecure computers and to computer tapes, seven of which remain missing. The defense contends the tapes were destroyed.