What do Atticus facial expressions and body and body language say about his emotions in this scene?

Atticus states that "The prosecutor concluded that he was guilty although Tom was black".

Explanation:

Facial expressions may say exactly what is going on one's head. As living creatures, we all are capable of communicating our feelings via our speech and acts. The language of humans body often is a useless gift to just the true feelings that we're passing along in our minds. Our eyes, this same small but noticeable convulsion of everyone's lips, the crumbling nose, etc., everything that unintentionally demonstrates our talents and inner feelings.

So that the above seems to be the right answer.