He murdered before? 115? Who was his visitor?
Why was Edmond writing to the woman about her daughter, whom he had gone to the prom with? I expected that he was going to confess in the letter that he killed her, but was interrupted by the prison guard, who came to tell him he had a vistor.
And who might his visitor haven been, when he told the guard to tell them he was sick?
Finally, what was the significance of his prison cell number, 115?