``I've lived a life of terror for 30 years that this whole thing would get found out,'' the 51-year-old unemployed coin dealer sobbed, tears gushing down his cheeks.
Lipka's change of heart was in response to a government offer to limit his prison sentence to no more than 18 years with time deducted for good behavior in exchange for his plea.
His lawyer, Ronald F. Kidd, said it was a plea bargain they couldn't refuse. Lipka was facing life in prison and had learned recently that the government would present damaging evidence against him at trial.
``I urged him to enter the plea,'' Kidd said after the hourlong hearing in U.S. District Court in Philadelphia. ``Under a worst-case scenario he will have to serve six to 10
years in prison.''
The evidence that could have put Lipka away for life was revealed during a closed hearing last month before U.S. District Judge Charles R. Weiner, Kidd said. It was from an unidentified government witness who was prepared to testify against Lipka.
``We saw how significant the evidence was,'' Kidd said. ``But the government also realized they couldn't go through a full trial and not have the mystery witness exposed.''
One of the prosecutors, Barbara J. Cohan, an assistant U.S. attorney, said yesterday that Lipka's plea was ``an appropriate resolution of this matter given the fact that this is a 30-year-old offense.''
She also acknowledged that the government was concerned about exposing its witness.
``We had a very sensitive witness who, if he had to testify, would have had to testify behind a screen and under an assumed name, and now we don't have to surface him at all,'' Cohan said.
There has been speculation that the witness was a former high-ranking Soviet official. When Lipka was arrested on Feb. 23, 1996, the FBI noted in an affidavit attached to the arrest warrant that Lipka was believed to be the ``young soldier at NSA'' whom former KGB Maj. Gen. Oleg Kalugin referred to in his 1994 book, The First Directorate.
Kalugin wrote that the soldier had ``passed on reams of top-secret material'' to the Soviets.
John L. Martin, chief of the Internal Security Section of the Justice Department, said Lipka's was the fifth guilty plea this year in a major espionage case.
Lipka's job at the NSA was to remove classified national defense documents from teleprinters and distribute them to various departments. The super-secret agency monitors communications around the world.
The government alleged that Lipka used miniature cameras to photograph classified documents. He strapped other documents to his legs or hid them under his hat to ferry them out of the building, authorities alleged. He later sold them to Soviet KGB agents and was paid $27,000 for his trouble, an amount that had greater significance in 1965, prosecutors said.
Those prosecutors said the classified materials included information about U.S. troop movements in Vietnam during the war.
In 1967, Lipka left the military and moved to Lancaster, taking with him NSA documents and meeting with Soviet agents as late as 1974, according to the government. Lipka denied those charges yesterday.
At the time of his arrest, Lipka was unemployed and living in Millersville with his second wife and two children in a small development among the cornfields south of Lancaster. His first wife, Patricia, had cooperated with the government in building its case against him.
``When I first got into it, I didn't realize what it all meant,'' Lipka told the judge yesterday. ``As I was doing it, I did come to realize and I did try to withdraw numerous times.''
Later, looking at a U.S. flag in the courtroom, Lipka said, ``I betrayed that flag. I'm sorry for that.''
Sentencing is scheduled for Aug. 15.