Who is William Davis?

Davis is another friend of Sweet's who comes the day they move. He spends the first night at the house. Davis is a federal narcotics officer who is arrested with the others the night of the shooting. He tries to separate himself from the others by giving the prosecutor a version of the story that they want, but it doesn't do him any good. He stands trial with the rest of them. He is not tried again after the mistrial.