The story was the possible defection to the United States of the grandson of Josef Stalin, the notorious Communist dictator and World War II hero of the Soviet Union.

The story's potential was all the more dramatic because the grandson's mother, Stalin's only daughter, had herself defected in 1967 and settled in the U.S., dealing the Kremlin a very public and bitter humiliation.

The tug of a hot story, and Krimsky's furtive pursuit of it in the shadows of the Kremlin during the spring and summer of 1975, was kept from the public eye for almost 35 years until it was uncovered by an author researching a book published this year.

In the end, the son's defection never happened. But the story behind it involves one of the most compelling human dramas of the Cold War, in which a prominent family was sundered by the machinations of the Soviet dictatorship. It also highlights some of the ethical dilemmas and professional risks facing journalists who were trying to cover the Soviet state.

Working in Moscow at a time of Cold War intrigues and Soviet repression of dissidents, Krimsky was considered one of the most tenacious reporters in the Soviet capital. He was ultimately expelled by the Soviets in 1977, less than three years after his arrival, but whether the possible defection attempt played a role is unknown.

Krimsky's Russian ancestry and command of the language gave him access to ordinary Russians and, more significantly, to many political dissidents, especially Andrei Sakharov, the nuclear physicist and 1975 Nobel Peace Prize laureate.

The defection story emerged in a series of secret meetings in public parks with Stalin's grandson, Josef Alliluyev, a teaching physician in Moscow, whom Krimsky met through an acquaintance of the grandson at a restaurant.

Alliluyev pleaded with Krimsky to help him arrange a visit to the U.S. to see his mother, Svetlana Alliluyeva, from whom he had been painfully separated when he was 22 and she left him to seek her own freedom in the West.

Foreign travel by Soviet citizens was strictly controlled precisely to prevent such defections from a country the former reporter described in a recent interview as then being "the biggest prison in the world."

The story first came to light this year in Nicholas Thompson's acclaimed book, "The Hawk and the Dove: Paul Nitze, George Kennan and the History of the Cold War," an account of the roles of two of America's most prominent policy advocates during the long ideological struggle with the Soviet Union.

Kennan was a huge influence in U.S. Cold War policymaking, and it was to him that Krimsky turned in a letter dated Aug. 5, 1975, and signed simply, "A Friend."

Sent to Kennan via the diplomatic pouch of the U.S. Embassy in Moscow, it said Svetlana's son wished to see his mother and he hoped she would send him an invitation to visit her in Princeton, New Jersey. To visit a relative outside the country, a Soviet citizen needed to show such an invitation in writing.

Thompson, an editor at Wired magazine, found Krimsky's letter and Kennan's memorandum on the matter while researching his book, and gave the AP copies of them. Krimsky confirms Thompson's account.

"His request, in short, is to visit his mother on a three-month tourist visa," Krimsky wrote. "Only later will he decide whether he wants to remain in the West. My own impression is that he has already decided to do so."

Kennan, by then retired from public life, spoke with Svetlana, who was his neighbor and friend.

"We came to the conclusion that it was unwise for both herself and the young man to try to communicate clandestinely and through third parties and that the best thing he could do would be to write her quite openly through the normal mails, concealing nothing from anyone, and tell her of his desire to visit her," Kennan wrote in his memorandum of Aug. 20, 1975.

Kennan said he should come only if he intended to go back to the Soviet Union. A defection "would be greatly embarrassing to her and to everyone else concerned," Kennan wrote.

Krimsky recognized he was crossing a line when he wrote Kennan.

"Understandably, as a newsman, I was interested and met the fellow," Krimsky told Kennan. "Since our first meeting in late June, my role has evolved into something less than a journalist's and more as a courier's - not without some soul-searching.

"If my actions become open knowledge, I stand to jeopardize my assignment here and, possibly, my job," he wrote. "Aside from the likely attitude of Soviet authorities, my own company has strict prohibitions against its newsmen getting involved in news events."

"As for me," Krimsky told Kennan, "I do not plan to return to the journalist's role in this affair until it is most advisable for Josef's security." But he concluded: "I would be less than candid not to say, however, that I would like to be on top of this news when it can be broken. If you have particular wishes in this regard, please convey them to me."

On a visit home later that year, Krimsky phoned Kennan's home, but Kennan's wife, Annelise, answered and told Krimsky he should drop the matter and she would not let him speak directly with her husband. Kennan died in 2005.

Krimsky said he also phoned Svetlana and they arranged to meet privately on a beach in Connecticut. Krimsky relayed news of her son, but an anguished Svetlana told Krimsky, on Kennan's advice, she could not invite her son because it might worsen U.S.-Soviet relations.

Returning to Moscow, Krimsky relayed Svetlana's response to her son. When he returned home again in December for the birth of his daughter, Alissa, Krimsky brought with him a letter from Josef to Svetlana and mailed it to her.

Back in Moscow the following month, Krimsky discovered a very frightened Josef, who had obviously been warned off by the authorities, apparently because his contact with an American journalist had become known. The two cut off communication and never met again.

In an interview at his home in the woods of Washington, Connecticut, and in later correspondence, Krimsky, 67, addressed the journalism ethics issues raised by his activities.

"I was conflicted about it because it did, in a way, step over a line, a very sensitive line, as far as the Western press is concerned," he said.

AP's rule was that it reported the news, it didn't make the news or get involved in the story, he said; secondly, writing to Kennan through the diplomatic mail was risky, but it was the only way for businessmen, journalists and others to deliver sensitive material. "I mean, the Soviet Union, not to be melodramatic about it, was literally the world's largest prison."

Krimsky says he revealed his activities to his Moscow superiors, chief of bureau David Mason and news editor Frank Crepeau, both now deceased. But there is no known evidence anyone ever notified AP's headquarters in New York.

Louis D. Boccardi, retired former AP president and the news agency's executive editor at the time, says he read about it for the first time in a New York Times story about Thompson's book.

"Unequivocally, no word ever reached me," Boccardi said. "I was totally surprised by the reference in the Times story." Boccardi said he was certain that if the late Wes Gallagher, who then headed the news organization, knew anything about it he would have told him.

"For survival reasons, the normal journalistic rules didn't apply in covering the Soviet Union in those days," Krimsky says. "For example, agency correspondents shared dissident news with their competitors, so no single journalist could be blamed by the authorities. That practice would have been anathema elsewhere."

Shunning the official version of the news from the controlled Soviet media, Krimsky said he made a specialty of covering the shadowy world of dissidents.