On the morning of Jan. 16, 1981, U.S. Customs special agent Richard Conger was at Dulles Airport as Braniff Flight 974 arrived nonstop from Lima. "All flights from Peru have potential problems--cocaine, currency violations, artifacts," recalled Conger. "I thought I'd stick around."

He didn't have to wait long. One of the customs officers stopped a man who had declared some pre- Columbian artifacts. "The odor coming from his suitcases practically drove us out of the search room," said Conger. "I asked why it smelled so bad. He said the things had just been dug up from graves."

That first whiff of trouble led, over the ensuing 18 months, to the discovery of bulldozed pre-Columbian cemeteries, a new bilateral agreement to stop trafficking in Peru's cultural treasures, and the return of hundreds of ancient artifacts--including gold death masks, textiles, ceramics, featherwork and silver goblets--to Peru. Today the Peruvian Embassy celebrates the artifacts' return with a reception and display of some of the recovered works.

Conger spent 10 hours that January day talking to the owner of the offending suitcases--a 34-year-old New York art dealer named David Bernstein. "I was trying to make a determination of whether this was a violation or not, and if so, of what," said Conger. (There is no blanket law forbidding the import of antiquities into the United States unless they are stolen and worth more than $5,000. Bernstein declared the value of his goods at $1,785.)

"I knew the stuff was valuable," said Conger. "I recalled a National Geographic article with a photograph of a preserved pre-Columbian girl-child, and knew that Peruvian textiles could be preserved in graves, and that feathers were even more rare and significant." But no expert would be available till Monday. Bernstein left, but Conger kept the suitcases in the Braniff cargo bay.

Next Monday morning, officials from the Peruvian Embassy were summoned to Dulles, along with the Smithsonian curator of Latin American archeology, Dr. Clifford Evans, a longtime champion of legislation to curb traffic in objects taken from archeological sites.

"I began to lay things out on the table," recalls Conger--"a gold death mask, ceramics, a feather cape, 154 objects in all--and Evans threw his hands up and said these came from sites from one end of Peru to the other, none of them known to scholars.

"He was very agitated, and said the feather cape alone was worth at least $100,000 in the art market in New York, and that we had nothing like that here, so well preserved. Finally, Evans said, 'I don't want to look at this anymore--it's making me sick.' "

A few hours later, the 60-year-old Evans suffered a fatal heart attack.

Since--and because of--the events of that day, much has happened, and all of it would have pleased Evans. A search of Bernstein's New York apartment uncovered 587 more Peruvian archeological treasures, leading to the biggest and most significant seizure of pre-Columbian artifacts ever, according to customs officials.

Today's reception marks the official turnover of 700 of these works to the Peruvian government. Appraised value: more than $1.5 million. Bernstein, in a plea-bargaining arrangement, pleaded guilty to a misdemeanor of filing a false customs declaration. He was given one year's suspended sentence, a $1,000 fine and 200 hours of community service. He also agreed to return his collection of art treasures to Peru.

"There was no charge, and no finding, that possession and/or sale of these antiquities was against the law," said Bernstein's attorney, Sheila Ginzberg Riesel. "His position is that he had a perfect right to own and sell these objects." She added that Bernstein's agreement to return the objects to Peru was in exchange for the government's not requiring him to cooperate with it.

Last fall, a bilateral executive agreement between Peru and the United States was signed, giving U.S. Customs the legal power to seize works of art removed illegally from Peru. In a 1929 law, Peru claims ownership of all pre-Columbian art unearthed after that date, and states that none may be legally removed from Peru without a license. "For the first time we have been able to do something big to stop this illicit trade," said Peru's Vice President and Ambassador to the U.S., Fernando Schwalb.

"Knowing the systematic depredation of our cultural heritage, and knowing that the United States is the largest art market for these things," said Schwalb, "I asked the State Department to enter into an agreement that would make it possible for them to act upon this traffic in a direct way. . . . It's not all over; as long as there's a market, there will be a problem. But people in this business now know that U.S. authorities have legal power to act."

(The U.S. has only one other such bilateral agreement, a treaty with Mexico. A UNESCO treaty, which would help control illicit trade in the cultural patrimony of all nations, was signed by the U.S. 10 years ago, but enabling legislation has never been passed. It is still pending before the Senate Finance Committee.)

Three other lots of Peruvian pre-Columbian artifacts have already been seized under the new agreement, and they, too, are being officially returned today. Since September, two Florida dealers have been stopped at Miami International Airport with $105,000 in Peruvian antiquities, and another dealer-collector was stopped at Dulles Airport with six items. There have been other seizures in New York, San Francisco, Los Angeles and Houston, according to Conger.

In Peru, surveillance has also been tightened. Bernstein had visited the country repeatedly, without being stopped, and had always declared his goods, according to his attorney. Now signs have been placed in airports clearly informing travelers of the new agreement, and customs inspectors there have been briefed.

According to Conger, Peruvians, Frenchmen, Panamanians and Americans were all connected with the collection, shipment and sale of Peruvian artifacts. "In Peru, there were seven arrests within the first month or two after the seizure here. They also stopped a shipment of 310 pieces bound for another American dealer."

Peruvian authorities found professional grave robbers who had prison records in Peru for artifact violations, Conger added. "One guy--subsequently arrested--had been caught in the act with a bulldozer in 1972 tearing off the tops of graves. He destroyed a whole cemetery just to get the textiles.

"Since then, I can't say we busted the whole ring, but we sure as hell put a crimp in the operation."

Conger will be among the U.S. Customs and State Department officials Ambassador Schwalb plans to thank publicly at the embassy today, surrounded by a small display of a few of the recovered objects--splendid examples in gold, silver, textiles, featherwork and ceramic dating from 800 B.C to the Inca period, which ended in 1532 with the arrival of the Spanish conquerer Pizarro.

Schwalb also plans to announce the creation of a nonprofit foundation to raise funds in the U.S. for the construction of a new museum of archeology and anthropology in Lima, a longtime dream of Peruvian President Fernando Belaunde Terry. All recovered items--past and future--would be deposited there.

The National Geographic Society has requested permission to show 300 of the returning objects in Washington next spring, and then circulate them to other American cities to help raise funds for the museum.

If the plan is approved, some importers of Peruvian art treasures will have helped not only to fill this new museum, but to build it.