I'm sure you have heard of Orson Pratt, 19th century LDS apostle, but I'm guessing you haven't heard much about his son, Orson Jr. Here's a paragraph from a post titled "Orson Pratt, Jr., Erastus Snow, apostasy and excommunication." at the Ogden Standard-Examiner's media blog Political Surf.
Orson Jr. was a lot like his father. Like his dad, he was an intellectual man who applied reason and evidence with faith. He was also an accomplished musician, talented enough to teach at the university level. Unlike his father, though, Orson Jr. was not able to reconcile his theological doubts with his respect for reason. He became a disbeliever of Mormonism, and in a very public forum in southern Utah, where he had been a member of that area’s theological hierarchy, Orson Jr. told a large crowd that he no longer believed Joseph Smith was a prophet or that Mormonism was the true church. His discourse took place in September 1864, the same month he was excommunicated at the urging of LDS Church Apostle Erastus Snow ....
I think most of his material is pulled from Gary Bergera's Conflict in the Quorum: Orson Pratt, Brigham Young, Joseph Smith (Signature, 1987), which the author cited in the post. I have never come across a copy yet, but it sounds like it would be worth a read.
According to the post, Orson Jr. lived a quiet life in Utah for forty years after his excommunication, dying in 1903 in Ogden.