The Snepp Case is closed, even if Frank Snepp is still ajar.

The Supreme Court slammed his door in February, ruling that Snepp had breached his contract with the CIA by failing to submit "Decent Interval," his critical book on the last days of Saigon, to the agency for pre-publication review.The court ordered him to "disgorge the benefits of his faithlessness." Since his book has sold well, the benefits were $140,000. Last week he gave the Treasury Department a check for that amount.

The case, which pits the right of the government to conduct certain business in secret against that of a citizen to speak his mind about what he has seen, is a hall of mirrors. What the mirrors reflect, among other things, are the fortunes and misfortunes of citizen Frank Warren Snepp III, late of the CIA.

As for the fortunes, there aren't any. Frank Snepp, as the consequences of the court's instruction to "disgorge the benefits of his faithlessness," is broke. He resides in a $411-a-month apartment (just raised from $300) in Arlington. He drives the same Capri automobile he had in Saigon. He is 37 years old and $40,000 in debt.

He relies on contributions for day-today life. They come from sources such as the Author's League Fund, a New York-based organization which a week ago sent him a loan of $5,000. And from former girlfriends around the world, particularly from a certain woman in Paris, to whom he is grateful, and about whose generosity he is embarrassed. He owns a phone and a typewriter. The typewriter is for the two more books he owes Random House. The phone doesn't ring very often anymore.

On the other hand, he is a free man. Here he is, strolling in front of the guitar player at Charlie's, a high-class musical eatery on K Street, to meet a companion for lunch. In his cotton-knight shirt, he looks like a CIA agent whose cover is that of a professional tennis player. He still feels like a member of the agency. But, although Snepp was the CIA's chief strategy analyst in Vietnam and won the agency's Medal of Merit for his work during the panicky final evacuation of 1975, the feeling is no longer mutal.

When Snepp wrote "Decent Interval," he traded the cloak of the spook for the craft of the creep, and to his former intelligence colleagues he is now a pencil-scratching mercenary turncoat, amoeboid slime born of the disorder of confusion and reatreat. Snepp hung the agency's dirty laundry out to dry. Now it's his turn.

"The Snepp Case is finished," he says. "Technically, three things could happen now to mitigate the punishment for writing my book. An executive order from the White House. A personal bill passed by Congress. Or the Justice Department could not seek to enforce the law. I have no hope for any of those things.

"There is, of course, an extreme sense of isolation. Most of my agency friends have long since headed for the hills, and my Vietnamese friends, too. You seek companionship where you can. I get calls from Edwin Moore, a man convicted of espionage. He has invited me to lunch. fBut I have not gone.

"You see, I am not radicalized. There is a society of whistleblowers here in Washington, but I'm too conservative for them. People lump me with Philip Agee, who exposed the names of agents. I'm totally opposed to Agee. pHe's a turncoat and a coward. He fled the country, rather than face the consequences of his actions. He should have stuck around, like Martin Luther King."

Snepp is also lumped with Victor Marchetti, author of "The CIA and the Cult of Intelligence," and with John Stockwell, another former intelligence officer who told about the agency's activities in Angola. All spies who went out in the cold.

"It's interesting," Snepp says, "that each of those guys had a deep religious background. Agee is a devout Catholic. Marchetti originally trained to be a priest. Stockwell's parents were missionaries. When they saw the agency not fitting into their view of things, their reaction was strong." The James Bond Ethos

Snepp's model was different. His father is a superior court judge in North Carolina. ("He's a political apppointee, and I believe you could say his upward career is finished. I do him the favor of staying out of North Carolins.") Recruited by a professor of his at the Columbia School of International Affairs, he says he always had great respect for the law, but a pragmatic point of view. h

"I believe you have to have a clandestine service. The CIA's nefarious activities are okay -- as long as they got the truth to Washington. When that principle was no longer served, as in Saigon in the end, we became the mafia."

In Saigon, Snepp served as an agent, an analyst and as an interrogator of prisoners in refrigerated rooms. There wer guns and whores and blackmail and terminations with extreme prejudice, all of which Snepp adjusted to well enough. What he did not adjust to, toward the end, was the CIA's disinclination to forward home what he saw as absolute proof that the war was unwinnable.

And he did not adjust well at all to the desperate pull-out of April 29-30, 1975, when the past hundreds of Americans were plucked by helicopters from embassy rooftops, and thousands of Veitnamese employes and friends were left behind. When he got home, he blew the whistle.

Snepp, who describes his own self-image of the time as "that of the James Bond romantic ethos," was a tough guy prepared to tell a tough story. He was prepared for trouble, he was prepared for the trials and tribulations of the contemporary American whistleblower.

What he was not prepared for was for the CIA and the Justic Department to land on him with both feet. Or for the Supreme Court eventually to find him not a brave maverick worthy of First Amendment protection but merely a government employe who had misused his office. An "errant fiduciary." The penalty was civil, not criminal. Disgorge the benefits.

The specifics of the disgrogement are these. In 1975, Random House advanced him $22,000 for "Decent Interval." The book had to be written and even printed in secret, because the CIA was intent on obtaining it for reivew. The book came out, Mike Wallace did a piece on "60 Minutes" and sales took off. But because a suit by the Justice Department had been filed, all Snepp's earnings went into escrow.

By last month, the escrow account contianed $11,000, $29,000 short of the amount he owed the government. Random House loaned him the extra cash -- at 10 percent interest. In the past two years, he says, he has lived on exactly $22,000 -- "most of it in the form of advances or quasi-advances against the next two books."

Not all of his misfortunes were monetary, however. When he started writing the book he had a girlfriend named Daphne Miller, who at the time also worked for the agency. The documents of the Snepp case show Daphne Miller's role in helping the agency determine who Snepp's publisher was.

Was he surprised?

"Surprised? I was appalled," Snepp says.

"The funny thing is," he adds, "she told them my publisher was Random House, which was what they needed to know is they were gong to stop publication. They didn't believe her."

Two documents introduced in Snepp's court records lend credence to his claim. In a CIA internal memo dated Jan. 14, 1976, covering an interview with Miller, it is noted that Snepp was "dealing with Random House in New York."

In an agency "routing and record sheet" titled "Mr. Frank Snepp's Literary Activities" and dated March 10, 1977, it is noted that "Mr. Snepp has written a book on Vietnam that is just about finished. The original manuscript finsihed. The original manufscript that Snepp is working with consists of about 900 pages. The publisher of the book is unknown but is located in the New York area."

Court records also contain a memorandum dated Jan. 5, 1976, and signed by Leo J. Dunn, cheif of operations of personnel security investigations for the CIA, in which Miller's situation is discussed. How she was "initially reluctant to discuss the matter." How she related a "rather sudden break-off" in her realtionship with Snepp. How she ahd promised to keep his project secret, but feared "that the book could do damage to individuals who remain in Vietnam." Now, Dunn wrote, she "stressed that the Subject is an extremely intelligent individual who likes the James Bond type adventure.He is said to be very calculating, and Miss Miller speculated that he might enjoy writing the book under the noses of security."

"The atmospherics were very strange," Snepp recalls. "I was being painted as a mercenary, as a wild man, and never once was there an open hearing. Never was there a jury. My best friends in the agency -- men who were painted as heroes in the book -- were simultaneously giving me classified information and working for the agency."

Snepp insists -- contrary to the popular notion of secret operatives as freindless paranoids -- that such lack of personal loyalty to him and his project came as a shock.

"The agency breeds paranoia, certainly," he says. "But it is paranoia of outsiders. You tend to invest more belief in your friends than you otherwise would. So I gave a great deal of information to Daphne Miller and to others. I was devastated by what they did with it." The Veneer of Fiction

Disgorge the benefits of your faithlessness.

In Arlington, his pencil continues scratching. He is "writing or his life," he says.Or at least for his bank balance.

"What Random House and I did was to strike a two-book deal. They wanted a book about the case itself. I wanted to do the novel." The case book, titled "Irreparable Harm," is finished in draft from. The novel is called "Convergence of Interests." It turns on the old question of whether there was a CIA operative involved in the assassination of President Kennedy.

Snepp says the publishing house has stuck by him throughout -- but that as a result, he now finds himself in a peculiar position.

"Because they've loaned me $40,000, I'm sort of an indentured servant. My novel is written in the 'In Cold Blood' style, like nonfiction. But my editor, who I'm afraid is very good, feels it needs to be more set scenes, more dialogue, etc. Because of the massive legal problems involved, it needs a veneer of fiction. It goes beyond that, because the editor believes in the Warren Commission report, and I don't believe the Warren Commission report. But because I have all these debts, I'm in a very poor negotiating position."

The banquette in Georgetown is very quiet, except for the sounds of the guitar. Snepp likes the place, although he says it gets pretty expensive in the evening. He goes occasionally to Clyde's, the polished-brass watering hole of the semi-young, "because there is a girl there I knew in Saigon." But most of the time, he works.

"I write in the mornings on the case book, then in afternoons on the novel. Or vice versa. Every day, I swim timed lasps for 45 minutes. I take Saturday afternoon off. I don't go to the beach, I don't go to cocktail parties, I don't reach out to people. Since 'Decent Interval' came out, I've gone through three or four girlfriends because of this regimen. There is currently a girl in New York who doesn't understand my travails, and she would like to pin me down. But i wouldn't subject anyone else to my life just now."

Life in the hall of mirrors. Snepp feels the Justice Department painted him as a gun-toting kook, a writermercenary, and that such "atmospherics" contributed to all aspects of his case. He thinks the image is wrong. And yet. . .

"When this all started a magazine photographer was taking my picture, and he said, 'You'll have of a lot of trouble. It's because you look the part.' And he was right, in a sense. I saw myself as romantic figure."

With a nod, he confirms a story of Vietnam. He and a friend are in a bar in Saigon, and two Vietcong come in shooting. Snepp flips a whore over his shoulder and runs upstars. The whore is bleeding because she has been hit in the leg, but she says to him, 'Your friend is still down there.' Snepp goes bakc down, and he and his friend grab the rifles from the Vietcong and beat them to death on the spot.

"It was different over there," he says. "If you look at it objectively, though, I do seem to continue even now to live life at the edge of crisis. But I don't enjoy it. I read George Meredith's "The Egoist' not long ago. Meredith says 'cynics are disillusioned romantics.' I've certainly become cynical, more cynical than I ever was in the agency. I've ended up disillusioned. But not to the point of repudiating the agency, you understand. That's what confuses people. One girl I met at a party looked at me and said, 'I know, you're a double agent.' No, I'm not.

"I was in Vietnam 4 1/2 years," he says. "During that time I took 12 vacation days. I was dedicated, and I believed in my job. We carried weapons, yes. Vietnam was a community of the heart, it's very hard to articulate if you weren't there. If you were there in the CIA, it's even harder. It changed you. Most of the women I've known since then are like me. They've been through some cataclysm. One friend of mine had cancer. One way or another, any friend of mine has emotional scar tissue." 'The Agency Always Wins'

Whatever it is that comes over his eyes at such times is not a faraway look. It is a look of frankness. A willingness to complicate his own equation. It is also a warning: You are not going to figure out Frank Snepp over lunch.

"The war provided certain cataclysmic moments," he says. "I used to make an effort to go out in the field, like the grunts, so as to understand it. mI was in a helicopter one morning, with other helicopters spread out against the sky, down in the Delta. We're flying along, and there on the horizon is the war. Artillery, columns of smoke. We're flying toward it, full of helicopter noise. I'd been reading 'For whom the Bell Tolls,' where Hemingway is telling you over and over how great was is. And I remember thinking, watching the tracer bullets coming up, how I wouldn't give up that moment for anything.

"You went over there looking for answers, and came back with questions. You know that scene in "The Best Years of Our Lives' in which Dana Andrews is walking among the carcasses of the B17s? A lot of us are doing that now, We'll always be doing it."

Victor Marchetti, who lives in McLean and who continues to write articles, recognizes the syndrome. He made "a quarter of a million dollars" on his book (shared with his agent and his co-author), but he remains ostracized, and says that's "something you never get beyond."

"When you buck the system, it doesn't matter whether you go right, like Frank, or left, like Agee, or whether you stay middle-of-the-road, like I did. You were picked for agency in the first place because of certain personality traits, and they're going to give you big personal problems. You're buffeted between guilt and the feeling that what you've done is worthwhile. The agency always wins in court. The loser in the end is going to be the guy who spoke out. He's going to get stomped. It's a goddamned lonely feeling."

Frank Snepp must know he lost. He has already submitted his new novel to the CIA for approval, and the CIA has already embarrassed itself by ordering a name out that it had previously approved in another manuscript, and then having to change its order to a "request."

John Stockwell has settled out of court, promising to pay any further royalties from his CIA-in-Angola book to the government. And to submit further writings to the CIA for review And the Justice Department is also after the profits of Philip Agee's two books, though they may be hard to collect. As for less problematical CIA writers, they are flocking to the review board. The CIA has examined 95 manuscripts so far this year, and 293 since 1977.

The agency's point of view on Snepp, as expressed by public information officer Dale Peterson, is this: "Mr. Snepp knew the rules. When he did not let us review his book, we felt we had to find out whether our secrecy agreement would stand up in court. It did. We intend to use that agreement against other former employes who attempt to publish without review. We will try to get injunctions, and stop the books.

"But look, the Marchetti case was a long time ago, and we've learned our lesson from it. We now know that we can delete only classified intelligence material, not just stuff that's embarrassing to us. We're very careful, we have specific guidelines. You have to understand that the agency hs matured. It's 30 years old now, and people are ending their terms of service. There are going to be a lot of books. We felt that with Snepp, we had to make a stand."

The strange thing about the whole business, despite the issues and the people who are reflected in the hall of mirrors, is that you can buy "Decent Interval" in downtown Washington right now. "When it came out in 1977, it was $14.95. Now it's on sale at $3.99.