Who is Jeff Farnley from The Ox-Bow Incident and what is their importance?

Jeff Farnley is a cowhand who once worked on a ranch with Gil. Farnley and Gil get into a fight at the beginning of the novel when Gil beats him at poker multiple times. Gil vows to return some of the money to Farnley, but does not have the chance because word of Kincaid's death causes Farnley to become upset and determined to track down the killers. It is Farnley who initially suggests they find the killers and hang them rather than allow the slow cogs of the justice system to allow them to go free. It is also Farnley who shoots Martin in the head when Young Tetley fails to hang him properly.