We called him what his Russian friends did - Sasha. His eyes crinkled warmly when he smiled, which was often. He and Ira, his wife, were much taken with our infant daughter and later, our baby son. Sasha brought roses when he came to our apartment for the first time, and considering that it was mid-winter in Moscow, those flowers were quite a treat.

What we did not known then and never would have guessed was that Sasha - Sanya L. Lipavisky - was an agent for the Soviet secret police, the KGB, and for a time, the CIA as well.

Thinking back on it now, I recall that Sasha - unlike most Russians we knew - rarely spoke about politics. He liked to chat, to brag, about his good physique. He was, indeed, a very youthful-looking man of 44 when we last saw him.

The story of Sasha Lipavsky - whom my wife and I probably knew as well as any foreigners in Moscow except his CIA contact - is important now.

He is virtually certain to be the main KGB wintess in the treason trial of Anatoly Scharansky, the young computer programmer who tried unsuccessfully to emigrate to Israel.

TR FOR ADD ONE

Scharansky was kind of a spokesman for "Refusemiks" - the Jews who wanted to leave the Soviet Union - and was active in the small group of dissidents monitoring Kremlin compliance with the human rights provisions of the Helsinki accords on European Security.

But Scharansky is not being prosceuted, as a dissident. He is alleged to be a spy. For that reason, the trial has particularly ominous Cold War overtones that American officials say could seriously damage U.S. Soviet relations.

It was a year ago - Friday, March 4, 1977 - that Lipavsky, in an "open letter" published by the Soviet government newspaper Izvestia, first accused Scharansky of being a spy.

Presenting himself as repentant Jewish dissident, Lipavsky described what he claimed was a complex collaboration between CIA operatives posing as diplomats in the American Embassy and a number of would be Jewish emgrants - with the cooperation of Western journalists. I was one of the reporters mentioned, a minor character in a grim tale.

Lipavsky's allegations were by far the most serious leveled by the Kremlin to that point in what was to become a major prograganda counterfofensive to the new President Carter's outspoken support of dissent in the Soviet Union under the banner of human rights.

The Soviet aim undoubtedly was to show that dissidents were subversives acting on orders from abroad - foreign agents. The Kremlin's hope was to discredit them in the eyes of the world, and especially in the West, where dissidents tend to be honored but treason is not.

The Izvestia article came as a shock. Americans in Moscow have to be on constant guard against KGB informers looking for ways to embarrass them. When any of us suspected a Soviet acquaintance, we stayed away from him.

Whatever else Lipavsky may have been, he was good enough at his mission to avoid detection.

Only a few weeks earlier, Lipavsky and Scharansky who was also our friend, had come to supper. It was not uncommon for dissidents to meet with Western reporters in their homes. Lipavsky looked pale and drawn. He said he had been fired from his job as a doctor in a clinic where taxi and bus drivers were examined before they got a license. Wetried to cheer him up.

Life was never the same for Scharansky after the Izvestia attack. He was followed everywhere by a cluster of KGB agents that he cheerfully called his "cage." At the end of two weeks, he was arrested - the only person among all the diplomats, dissidents and journalists named by Lipavsky against whom action was taken.

Lipavsky, not surprisingly disappeared. When I, like other reporters, telephoned his home, his wife said he had gone on a trip to Tashkent and would be back in a week.

It was easiest to discount Sasha's story as nothing more than a kremlin blast in the continuing ideological warfare between East and West. Other dissidents told us that behind Sasha's casual demeanor, he had complained of problems that might well have made him very susceptible to an offer from the KGB.

Lipavsky's aged father had been released after serving 13 years of a 15-year term for blackmarketeering. The old man was always a candidate for further trouble.

Lipavsky's son, an army private, was in custody. He supposedly had struck an officer some months earlier for calling him a "dirty Jew."

Lipavsky himself, as a doctor, was surely susceptible, it was said, to bribes from other doctors who might have needed his connivance in obtaining a license. Bribes were not unusual in cased like that.

His father. His son. Himself. How could he have resisted KGB pressure to sign his name to that article?

Nevertheless, we had some nagging doubts. Why had the U.S. Embassy's denial, calling the Lipavsky article "a classic example of disinformation laced with slander and innuendo" been so vague - the sort bureaucratic" cratic phraseology that did not rule out that elements of the story might have been correct.

This week, the reason became clear. Time Magazine reported, and administration sources confirmed, that Lipvasky was in part telling the truth about at least one person: himself.

He had been a CIA agent for about nine months in 1975 - what the agency calls a "walk-in" - who offered material on what he said might be of scientific, demographic or social usefulness.

It is fair to assume, intelligence experts say, that Lipavsky was already working for the KGB when he made his approach to te CIA. He was also assigned, they believe, then or maybe later to penetrate the dissident community.

The CIA ultimately dropped him sources say, because it doubted his reliability. Naturally, the agency never warned anyone else.

We met Lipavsky in November, 1974 at a dinner in the home of a would-be emigrant. It was the weekend that Moscow and Washington were said to have reached agreement that the Soviet Union would permit increased Jewish emigration in return for trade benefits. I wrote a story about the reaction of those present that evening.

After that, we saw lipavsky once every months. In the spring of 1976, apparently after his CIA period, he gave me a fascinating document that contained instruction sent to meat plants throughout the Soviet Union on how to reduce the meat content of sausage, increasing the amount of scrap, without telling consumers.

It still strikes me as odd that a KGB agent would leak such a document. But this mystery seems destined to remain unsolved.

On several occasions, Lipavsky also asked me for books from the West. This was hardly suspicious. We rarely met a Soviet - from high-ranking officials on down - who did not ask for Western reading material of some kind. Once, we received a letter from an emigrant couple living in Israel containing a note for Lipasvsky. We gave it to him. He thanked us effusively.

The problem in the disclosure that Lipasvsky had worked for the CIA, according to American officials and Jewish groups here, is that it makes it seem plausible that Scharansk was somehow also involved with the CIA.

Senior American officials insist that this is simply not so.

American officials - eventually including President Carter - have repeatedly denied that Scharansky "had any known relationship in a subversive way or otherwise with the CIA."

Thus with the President Carter's credibility on the line, an obscure young technician - who only wanted to leave the Soviet Union as tens of thousands of other Jews had done before - hs become a consequential figure in superpower politics.

Unlike Andrei Sakharov, the great physicist, or Alexander Solzhenitsyn, the great writer, Scharansky is a very ordinary person.

So, we thought, was Lipavsky.