Butch Cassidy and the Sundance Kid’s Parting Shot : The outlaws left a string of legends, and a mystery. Hot on their final trail is a husband-wife research team.

Butch and Sundance. Now there’s a neat little mystery.

Were the famed outlaws really killed in Bolivia after a shootout with troops? Did Butch Cassidy kill the Sundance Kid, then do himself in, rather than be captured? Or did they escape and live out their lives, as lore has it, in such disparate locales as France, Uruguay and Spokane, Wash.?

Such is the stuff of legend about Butch Cassidy and the Sundance Kid, whose given names were Robert Leroy Parker and Harry Longbaugh and whose story was made even more famous by the 1969 movie starring Paul Newman and Robert Redford.

The ending to the movie was deliberately vague, but now the answers to some of the aforementioned questions may indeed be in the offing, thanks to a couple who became infatuated by the tale, as well as with the wonders of modern forensic science.

Their latest hunt began around Christmas of 1985, when the Washington, D.C.-based husband-wife research team of Daniel Buck and Anne Meadows were vacationing through the Patagonia region of Argentina. They had read that the outlaws, accompanied by their companion Etta Place, had fled to South America around the turn of the century. One reason: The telegraph and other modern methods of communication had made robbery a much riskier business.

“Technology was catching up with them,” said Meadows. “Most of their pals had either been killed or jailed. We believe they wanted to go straight when they went to Argentina.”

Not only did they find the place where the trio lived peaceably for several years before returning to crime, they even found the ranch buildings intact. Curiosity aroused even more, the two started looking into the history of the outlaws and found there were no fewer than two dozen versions of how they had died.

“Outlaw history is a perfectly named field,” said Meadows. “When people . . . were using aliases half the time, when they were always trying to cover their tracks, it’s very difficult.”

Thus began a six-year look at Butch and Sundance, with Buck spending the initial months poring over documents in the Library of Congress and the National Archives. They discovered, among other things, that there had been no original research on the subject of the outlaws in South America and that most of the people who wrote about the two did not even speak Spanish.

Eventually Buck came across some diplomatic correspondence that made note of a shootout between a couple of Anglos and troops in the Bolivian mining town of San Vicente.

And so the researchers went to San Vicente, a desolate, barren spot high in the Andes mountains. It was there that they met Friolan Risso, who told them the story passed on to him by his father of the two men who had been killed and buried in the village cemetery.

Last year, Meadows and Buck returned to San Vicente for the third time, but this time they brought with them one Dr. Clyde Snow of Norman, Okla., a noted forensic anthropologist whose work had helped identify plane crash and murder victims.

“That was one of the roughest times I’ve ever had in my life,” said Snow. “I’ve been in a lot of tough places, but this takes it. It was cold. There was no water. You can’t breathe. That place is the end of the earth.”

Directed to an unmarked grave, the researchers dug up the remains of one man and a few bones from another. They were given permission to bring the remains back to the United States, where they are now being subjected to a battery of tests to see if it can be determined that Butch and Sundance were the men killed in the village on Nov. 6, 1908.

So far, Snow is not discussing the preliminary findings, though the circumstantial evidence seems to indicate that the famed outlaws did indeed meet their end in San Vicente.

But Meadows also said she was realistic enough to know that even if Snow’s forensic tests add to their body of evidence, the question of where Butch Cassidy and the Sundance Kid died will not be solved to everyone’s satisfaction.

“Outlaw historians are going to continue arguing about it forever,” she said.

She also said people have asked her over the years why she and her husband had spent so much time on this case. Why direct their research skills on nothing more than a couple of criminals and how they met their demise?

“The point is, it’s a mystery,” she said.