One of the books reviewed in True West is Butch Cassidy, My Uncle, by Bill Betenson. His great-grandmother also had a book, Butch Cassidy, My Brother. And I'm waiting for one called Butch Cassidy, My Cousin, or Butch Cassidy, My Fourth Cousin's Outlaw Great-Uncle or such. According to the review there is no new information regarding Cassidy's life after Bolivia, but the book does provide more info on the family and the outlaw with more research material available now than earlier. I wouldn't mind giving it a read to satisfy my inquiring mind of the new details, since he is always a good subject to read and write about. A fine review by Mike Bell, author of Incidents of Owl Creek: Butch Cassidy's Big Horn Basin Bunch.
This reminds me of an old high school friend, who claimed to be a relative of the Parker (Cassidy) family and whose name was Parker. Whether he was telling the truth or not, I don't know, but he was pretty convincing. We both attended the same school in Utah and he had a real good sense of humor. I can see him now writing Butch Cassidy, My Idol, The Further Adventures of the Robin Hood of the Old West. It would've been a humdinger of a novel and a fantastic movie epic after the Broadway play had run its course, however, he has gone to meet his maker. When or how, I don't know. Just like Butch Cassidy.