Records show that a rustler named Edward H. Seeley was imprisoned at Wyoming Territorial Prison while Cassidy was there, Pointer said.
"That's just really exciting to me because this is really ephemeral stuff," he said. "No one who had not been there or done that would know that."
Nobody except for some cowboy who rode the range in the late 1800s, knew Cassidy's friends and maybe even knew the outlaw himself, Buck suggested.
"There's a sort of commonsense reason why Phillips would have got some stuff right," Buck said. "They knew each other."
In 1991, Buck and his wife, Anne Meadows, helped dig up a grave in San Vicente, Bolivia, said to contain the remains of Butch and his sidekick, Harry Longabaugh — the Sundance Kid. DNA testing revealed the bones weren't the outlaws, but Buck, a writer who lives in Washington, D.C., said his research proved the two indeed died in a shootout with Bolivian cavalry in 1908.
Stories abound of Sundance living long after his time in South America. But they're outnumbered by purported Cassidy sightings. A brother and sister of Cassidy's insisted he visited them at a family ranch near Circleville, Utah, in 1925.
"The majority of those who were there believed that, believed it was him that came back," said Bill Betenson, who recalled that his great-grandmother, Lula Parker Betenson, used to talk about the visit by a man she identified as her brother, Cassidy.
The manuscript has an ending fit for Hollywood. Cornered by the Bolivian cavalry while holding up a pack train, Butch and Sundance make a stand. Sundance is killed. Butch escapes to Europe, has plastic surgery in Paris, and schemes to return to the U.S. and reunite with an old girlfriend from Wyoming.
Most of the manuscript's accounts bear little resemblance to known Wild Bunch exploits. Pointer insists that Cassidy, as Phillips, was writing fiction. Phillips did offer the story to Sunset magazine without drawing interest.
The earliest documentation of Phillips is his marriage to Gertrude Livesay in Adrian, Mich., in 1908, three months after Cassidy's last known letter from Bolivia, according to Pointer. Buck insists they married several months before a documented Bolivian shootout that probably was the one in which Butch and Sundance were killed.
In 1911, the couple moved to Spokane, where their closest friends said years later that Phillips let them in on a secret: He was the famous outlaw.
In the 1930s, Phillips sold his interest in the foundering Phillips Manufacturing Company. He visited central Wyoming, where more than a few people in the Lander area, including one of Cassidy's old girlfriends, said it was Cassidy who spent the summer of 1934 camping out in the Wind River Range, telling tales about the Wild Bunch and digging holes in search of buried loot.
"All of these people were bamboozled by this faker from Spokane ...?" Pointer said. "These weren't hayseed, duped ignorant people. These were pillars of our community. And if they said something, you had to better take it seriously."
Phillips' adopted son, William R. Phillips, believed his stepfather was Butch Cassidy, said Pointer, who interviewed him in the 1970s. William R. Phillips has since died.
In 1938, after her husband died of cancer, Gertrude Phillips told a Cassidy researcher that she and her husband had known Cassidy but that Phillips was not him. She did so only because she "didn't want the notoriety," Pointer said William R. Phillips told him.
DNA testing is unlikely to determine that Phillips, who was cremated, was Cassidy.
The many reports of later Wyoming sightings have convinced Carol Thiesse, director of the Fremont County Pioneer Museum in Lander.
"If Phillips wasn't, he certainly knew a heck of a lot about Butch," she said.
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