Every major trial gives a kind of instant fame to key witnesses, but the trial of Ronald W. Pelton goes beyond that, with witnesses and spectators cast in roles straight out of spy novels.

The espionage trial of Pelton, a former National Security Agency analyst accused of selling U.S. intelligence secrets to the Soviet Union, has given to everyday people the vivid dimensions of characters caught up in international intrigue and the twilight struggle between East and West.

Among the people for whom real life has become stranger than fiction is Ann Barry, Pelton's former lover, whose appearance at the courthouse Thursday stirred the excitement among news photographers one would expect for the arrival of Jacqueline Onassis. Barry managed to elude photographers easily on her way in, but on her way out she had to speed from a parking garage in a car that ran a red light and nearly plowed through the camera crews.

Two men conferring in hushed, heavily accented English outside the courtroom drew stares from a few reporters Thursday who mistook them for Russians. When one of them, George Alexakis, was called as a witness, he turned out to be the proprietor of a Falls Church pizza parlor who was asked to identify photographs of a wall phone at his restaurant where Pelton allegedly received calls from Soviet handlers.

One man in the spotlight who no doubt looks back fondly on his days in obscurity is FBI agent Daniel Brennan. His tangled testimony Friday appeared to embarrass the prosecutors as much as it amused Pelton's defense lawyer.

On a government tape recording of a telephone call allegedly made by Pelton to Soviet officials at 4:53 p.m. on Jan. 15, 1980, the caller, when invited to go right over to the Soviet Embassy in Washington, says it will take him a half-hour or more to get there. Prosecutors gave Brennan the task of timing automobile trips from Pelton's home and work sites in Maryland to the Soviet Embassy, in order to show that the crime was initiated in Maryland and that the U.S. District Court in Baltimore is the proper forum for trial on that espionage count.

Brennan testified that it took him precisely 30 minutes to drive to the embassy from Bladensburg, where Pelton worked. But, under cross-examination by defense attorney Fred Warren Bennett, Brennan was asked why he made the trip at 10 in the morning instead of during the evening rush hour, when Pelton was allegedly estimating his driving time. "I drove it at 10 a.m. because it would be faster, traffic would be lighter and it would get me there sooner," said Brennan.

Bennett, clearly delighted at that answer, pressed on, noting that Brennan appeared to have taken a "back route" when timing the trip from Pelton's home in Bowie.

The spectators gallery, which has room for about 60 people, has been filled to capacity each day with reporters, artists, a few court watchers and a sizable contingent of government representatives from the FBI, the Justice Department and the super-secret National Security Agency, where Pelton worked for 14 years. CIA Director William Casey's warning to the media last week to avoid "speculation" on U.S. intelligence losses caused by Pelton's alleged disclosures has only increased the size of the crowd. Asked whether the FBI had spotted any Russian operatives among the spectators, one FBI agent replied jokingly: "Russians? No, why should they be here when they can get it all in The Post?"

Other personalities who have drawn attention at the trial, which goes into its fifth day with the opening of the defense's case today, are members of Pelton's family. His wife Judith, a nursing supervisor from whom he was separated last summer, has been visiting him in jail regularly and attends the trial daily. All three of Pelton's daughters sat through portions of the trial last week, as did his 36-year-old brother Mark Pelton, who said he made the trip from his home in Texas to lend the family moral support.

During one particularly painful moment for Judith Pelton, Mark Pelton reached over and squeezed her shoulder comfortingly. That came when Ann Barry -- a teen-age beauty queen a decade ago -- took the witness stand for the prosecution dressed in a chic, silky white dress and dangling earrings.

Barry, the government has said, began seeing Pelton in 1984 and introduced him to a life style that included heavy drinking and drug use.

Pelton, who the prosecution claims has caused grave damage to the United States' capabilities of monitoring Soviet communications, remains the most riveting character in the courtroom, though he has not said an audible word.

If he testifies, perhaps he will explain what has been a major subject of speculation throughout the trial: How, in the years since 1979, a brilliant middle-management NSA analyst, an overweight, churchgoing family man, became, as the government contends, a high-living wheeler-dealer who would sell some of his country's most vital secrets for $35,000 -- pocket change for the fast life.