It's been years since I've seen this, but (spoiler)
Who was he accused of murdering?
shareRichard Gere's character was accussed of murdering a man by the name of Horace Townsend. Gere's character tells Laurel in the prison scene that the dead man was the real Jack Sommersby and Horace Townsend was Gere's real name before he pretended to be Jack Sommersby.
Hope that makes sense.
No it was Charles something or other...
shareCharles Conklin. Horace Townsend is the real name of the man pretending to be Sommersby.
http://www.script-o-rama.com/movie_scripts/s/sommersby-script-transcript-gere-foster.html
Search the script for "Conklin" to get the story. The death was over a game of cards. The real Sommersby was stabbed the same night, died, and was buried by Horace Townsend, who then took over the identity of Sommersby.
Incidentally, in the descriptions of the fight, it could be interpreted that Sommersby went down so hard and lay there when Charlie Conklin first "hit" him because Conklin had, in fact, knifed him in the stomach then and there. Which would make the shooting, depending on the laws of the time, self-defense. This defense was unavailable because only the body of the real Sommersby had a knife wound from Charlie Conklin's knife.