Andre Prestes and Vera Campos, sought in Washington on charges of stealing $1.55 million in the first money market fund embezzlement in American history, surfaced in their native Brazil yesterday and claimed they were innocent victims of a computer error.

Prestes said he learned of what he termed the "error" when he called his Rosslyn bank on May 2 -- three days before the alleged theft -- and was told he had an extra $1.55 million in his personal checking account.

"I was very surprised," Prestes said. He said his girlfriend, Campos, "fainted in the car" when she heard the news.

Court papers say that on May 5, Campos, a clerk in the accounting department at First Variable Rate Fund for Government Income, authorized an illegal transfer of $1.55 million in First Variable funds to Prestes' bank account in Rosslyn. After withdrawing $50,000 in cash and transferring the rest to a bank account in Switzerland, FBI officials said, the two fled the country.

According to the FBI, the scheme wasn't complicated; it only took some falsified papers and a bit of creative addition to make it work. But accountants at the fund, Washington's largest, didn't discover the loss until almost a month later. For a few tense days until the money -- plus an additional $15,000 that authorities say is of questionable origin -- was found in the Swiss account and frozen, it seemed as if someone had pulled off the perfect crime.

But Prestes, talking to reporters outside a police station in Campos' home town of Belo Horizonte, had another story. Smiling and self-confident, and wearing a white shirt open to the naval and a gold medallion on his hairy chest, Prestes said he had called his Rosslyn bank on May 2, as he said he did every three days while he lived in the U.S., and a clerk told him of the extra money in his account. "I told them this wasn't Christmas," Prestes said.

"There was a computer error at the First Variable Rate Fund," explained Prestes. "They cooked up an excuse for the error, alleging there was a con job." Prestes claimed he consulted several American lawyers -- none of whom he would identify -- about his predicament, and that they advised him to deposit the money in Switzerland, among other things.

The FBI said yesterday that Prestes' story "is very dubious." According to the FBI and other sources, no computer was involved and the wire transfer was set up well in advance.

In any case, the U.S. has no extradition treaty with Brazil, and the FBI can only hope Brazilian authorities will cooperate. The pair could be tried by Brazilian court, but a Brazilian federal police official who interrogated Prestes and Campos said yesterday that there were no formal charges against the pair, and that if they wanted to leave Brazil, they are under no legal restraints.

From the moment they came here from Brazil on tourist visas three years ago, Prestes and Campos had been concocting strike-it-rich schemes. They tried vending. They told friends of their plans to run charter jets to Disneyland or smuggle diamonds from South Africa. They considered opening a boutique in Georgetown and manufacturing T-shirts with snappy sayings. Prestes went to Control Data Institute to learn computer programming.

And at one point, when they feared deportation as illegal aliens, the two scraped up $1,000 to pay an American woman to marry Prestes in a plan that included a quicky, Dominican Republic divorce and a remarriage to Campos.

But no matter how hard they tried, nothing seemed to work for the daughter of a gas station owner and the son of an encyclopedia salesman.

In some ways, First Variable was the perfect target for the alleged scheme, the kind that the FBI is calling the Crime of the Eighties (white-collar embezzlement responsible for between $40 billion and $100 billion in losses last year).

Founded by two young former Wharton School of Business classmates in 1976, First Variable Fund's portfolio of long- and short-term government securities had grown to almost $800 million by the time Vera Campos was hired there.

Some say that the fund grew too fast for its own good. Indeed, this week, experts at the fund are putting finishing touches on a computerized accounting system that fund officials say would have made it impossible for the alleged embezzlement plan to succeed.

On the humid afternoon of May 5, Campos sat at her tiny deks in the cramped, third-story office in the share-holder transfer accounting department at First Variable that she shared with five others. Her supervisor, Kathryn Taylor, had just left the office on business. Campos had worked there for five months, getting hired despite a resume that claimed she had worked for two companies, which later proved to be false. She was, according to the fund's general counsel, Wayne Bardsley, "in all regards almost a perfect employe."

Before leaving the office that day, Taylor had called Riggs National Bank and advised the bank that 13 wire orders authorizing the transfer of money from the fund's trust account at Riggs to various shareholders would be coming to the bank by messenger.

But now Taylor had gone, and according to court papers, Campos reached for a blank transfer order and rolled in her typewriter, filling in: Virginia National Bank, account number 43348351, Andre L. Prestes, $1,555,000. Under the name of the bank she wrote in Rosslyn Branch by hand.

Records show that Prestes had opened the Virginia National account and rented safe deposit box No. 10 on Sept. 22, 10 days after he stopped working at TDX Systems, a telecommunications firm in Vienna. A short time before Prestes left TDX, the firm reported $10,000 stolen. The FBI is looking into Prestes' possible involvement in that theft.

When Prestes opened the Rosslyn Branch account, according to court records, he asked about wire transfers and foreign money transactions. In April, after Prestes opened a $2,500 investment account with First Variable, he allegedly asked bank officials again about wire transfers, inquiring about the cost and the length of time they customarily took to go through.

Now, the transfer was in motion. Had the usual controls at the fund been in effect, it would have never gotten this far, according to officials at the fund. Had someone checked, the transfer would have been denied.

The Riggs messenger picked up the wire orders from Campos' office and made three copies of each. The copies of the fradulent transfer to Prestes have since disappeared, authorities say. A short time later, a Riggs official called Campos' office and told someone that he had received 14 orders from the messenger, one more than Taylor had earlier advised him he would be getting. The total was now $1.55 million extra.

Campos allegedly authorized the bank official, R. J. Gatton, to go ahead with the transfer. He did so, even though the orders lacked the two required signatures of First Variable officials.

Later that afternoon, with Campos' supervisor still out of the office, the computerized receipts for the transfers were returned to First Variable from Riggs. Normally the assistant comptroller receives the computer-printed receipts in one long strip. This day, however, one receipt -- the one confirming the transfer to Prestes -- had been torn away. The assistant comptroller received two strips of uneven lengths.

Next, authorities allege, Campos entered the $1.55 million on the daily ledger, but added the column of figures wrong, so that the transfer to Prestes would not be reflected in the days tally. The writing on the original transfer request and that in the ledger, according to Campos' supervisor, was hers.

Two days later, shortly after 12:30 p.m., records indicate that Prestes withdrew $50,000 in cash from Virginia National's Pentagon Concourse branch. At 1:26 p.m., records show, he put something in his Rosslyn safe deposit box.

The next day, May 8, Campos received a telephone call shortly after 2 p.m. She went to another supervisor, Maura Dyer. Tears forming in her eyes, Campos told Dyer that "Louie," as she sometimes called Prestes, had been in a car accident in Ohio and was being flown back to Washington. She left work to meet his 2:30 p.m. flight. She never returned.

On May 11, according to court documents, Prestes went again to his Rosslyn bank, carrying a leather briefcase. After going to his safe deposit box, he asked the bank to transfer by cable $1.5 million left in his Rosslyn account to an account at the Union Bank of Switzerland, court papers said.

In Brazil yesterday, Prestes claimed that the transfer was not made until May 21, after he had "waited around" a week for "a call from the First Variable."

Prestes was last seen in the U.S. on the afternoon of May 22, in the parking lot outside the one-bedroom apartment he shared with Campos at Oakwood, a singles complex in Alexandria. He was seen loading a bicycle, a 4-foot teddy bear and several suitcases into an old green Buick.

The night before, his neighbor at Oakwood, Joan Vieira, recalled, Prestes stopped by her apartment, offering a stereo set, a toaster oven, stereo records and other appliances for sale. "I asked him if he was being transferred," Vieira said.

Prestes said, "I'm going back to Brazil to get some better money," according to Vieira.

Today, First Variable is working through legal channels to have the money that was frozen in the Swiss account returned. The $50,000 that Prestes and Campos allegedly took had been invested in gold, according to their Brazilian lawyer.

In some quarters back home, Prestes and Campos have become a legend, a Brazilian Bonnie and Clyde romanticized by the people. When news of the embezzlement hit Brazil, Carlos Eduardo Novaes, the Brazilian Art Buchwald, wrote, "It is one of those times when I am proud to be Brazilian . . . We are producing international con artists . . . We are no longer an undeveloped country."