Shirley Utz and her husband were watching the movie "Country" at Springfield Mall Cinema when it happened -- probably, said Utz, at the point in the film "when a tornado comes along and it gets real loud and noisy."

Utz and about 20 other women, testifying last week in federal court in Alexandria, described the theft of their wallets from their purses while they were engrossed in a movie. Many of them did not realize they had been robbed until several hours after leaving the theater, they testified.

By that time, the thieves, using credit cards stolen in the theater, had purchased nearly $28,000 worth of expensive items at a nearby jewelry store, Diamonds Unlimited. The shop owner, David Lee, 27, has been found guilty of conspiracy and fraud for his participation in the scheme by accepting credit cards he knew were stolen.

The elaborate credit card scam, which lasted almost a year during 1984 and 1985, was outlined by witnesses at the two-day trial of Lee, the first area retailer tried and convicted on charges of credit card fraud as the result of a nationwide effort by federal authorities to crack down on merchant collusion in credit card abuse.

Lee and four other area merchants were arrested in December in an undercover operation code-named Operation Wildcard conducted by the U.S. Secret Service and local police departments, according to Secret Service spokesman James Lucey. One of the merchants has pleaded guilty to charges of credit card fraud and charges are pending against the other merchants.

Spokesman Dan Brigham of Visa USA Inc., estimated that 20 percent of credit card fraud cases involve merchant cooperation. The U.S. Secret Service, which was given responsibility for credit card crimes in 1985, has made the problem one of its top priorities, Lucey said.

A spokesman for Mastercard International Inc. said the company estimates that it lost $65 million last year through credit card fraud; Visa's Brigham put his company's loss at $95 million. Spokeswomen for Choice and American Express said they do not release figures on credit card fraud.

At Lee's trial before U.S. District Judge Albert V. Bryan Jr., government witness Susan Breedlove testified that she and her boyfriend took their seats before the shows began and stole the wallets "after the couple was into the movie." Diamonds Unlimited "would always be my first stop," said Breedlove, who is being held on credit card fraud charges.

She said Lee knew the cards were stolen because "I would come to him . . . two or three times a day with a different credit card."

Lee denied that he knew the cards were stolen. Questioned by prosecutor Larry Leiser as to why he accepted several credit cards with men's names during a transaction with a female Secret Service undercover agent, Lee replied: "I was not paying attention to the names."

Mary Anne Cummins, who had $1,200.18 in unauthorized charges appear on her stolen card, said last week she couldn't remember what movie she was seeing, but "it wasn't worth it, whatever it was."

Secret Service spokesman Lucey said statistics were not available on the number of retailers who have been arrested nationwide.

Many merchants say they are grateful for the attention. "We think it's doggone good for the Secret Service to be getting into that," said Sumpter T. Priddy Jr., president of the Virginia Retail Merchants Association.