The present owner is a museumand more informatin can be found here. This story was also related in an issue of finewoodworking magazin a number of years ago.
http://urbanlegends.about.com/library/bl_mysterious_staircase15.htm The subject of rumor and legend for over a hundred years, the riddle of the carpenter's identity was finally solved in the late 1990s by Mary Jean Straw Cook, author of Loretto: The Sisters and Their Santa Fe Chapel (2002: Museum of New Mexico Press). His name was Francois-Jean "Frenchy" Rochas, an expert woodworker who emigrated from France in 1880 and arrived in Santa Fe right around the time the staircase was built. In addition to evidence that linked Rochas to another French contractor who worked on the chapel, Cook found an 1895 death notice in The New Mexican explicitly naming Rochas as the builder of "the handsome staircase in the Loretto chapel." This demonstrates among other things that the carpenter's identity was not a mystery to residents of Santa Fe at the time. At some point, presumably after the last remaining members of the generation of Santa Feans who witnessed the building of the Loretto Chapel firsthand passed away, Rocha's contribution to the Loretto Chapel faded from memory, and history gave way to legend. As to the mystery of the origin of the wood used in the construction of the staircase, Cook theorizes that it was imported from France -- indeed, the entire staircase may have been built start to finish in France and shipped intact to America.
Thank you very much for the detailed clarification on the staircase. Have you found an explanation anywhere in your research, as to how the mysterious stranger story began? One might conjecture the tale started as a way to introduce strangers to a wonderful, carpenter saint ... any thoughts?