Charles Romer, a retired oil company executive from Scarsdale, N.Y., and his wife, Catherine, were driving back from their winter home in Florida in the spring of 1980 when they stopped at a Holiday Inn in Georgia.

Later, the police would find their belongings unpacked in a room at the hotel, along with a half-full bottle of Scotch and some glasses. The bed was turned down. But the couple — and their late-model black Lincoln Continental — were nowhere to be found.

For decades, the disappearance was shrouded in mystery, as relatives of the couple searched for answers. The police long suspected that the couple may have been killed in a brutal robbery, as Ms. Romer, a beloved socialite, had a considerable amount of valuable jewelry with her.

Last week, the first big break came in the four-decade case, after volunteer divers visited Brunswick, Ga., a coastal town about 75 miles south of Savannah, and found a car similar to that of the Romers at the bottom of a pond near their hotel.

The divers — who use sonar equipment to find submerged vehicles as part of an effort to find missing people — had seen the Romer case on a map of unsolved cases involving people who had disappeared with their cars. On Friday, they started scanning every body of water within several miles of the hotel where the couple had disappeared. In a 10-foot-deep pond near a parking lot of what is today the Royal Inn, they said, they found a vehicle with characteristics that matched that of the Romers — and in it human bones.

“It came out of the blue,” said Lawton J. Dodd, a spokesman for the Glynn County Police Department in Georgia. “It’s a cold case that is not a cold case any longer,” he said. “The investigation’s reopened.”