Why does Holmes eliminate Mr james from the list of suspects?

Near the beginning of chapter 6, we find the following quote from Sherlock Holmes:

". . . I have made some inquiries myself in the last few days, but the results have, I fear, been negative. One thing only appears to be certain, and that is that Mr James Desmond, who is the next heir, is an elderly gentleman of a very amiable disposition, so that this persecution does not arise from him. I really think that we may eliminate him entirely from our calculations. . . ."

Near the beginning of chapter 6, we find the following quote from Sherlock Holmes:

". . . I have made some inquiries myself in the last few days, but the results have, I fear, been negative. One thing only appears to be certain, and that is that Mr James Desmond, who is the next heir, is an elderly gentleman of a very amiable disposition, so that this persecution does not arise from him. I really think that we may eliminate him entirely from our calculations..."

http://wiki.answers.com/Q/Why_does_Holmes_eliminate_mr_James_desmond_from_the_list_of_suspects_in_hound_of_the_baskervilles