Alan, the green portion of clothing could be part of the black guy's white shirt. He is standing below and to the right of Lovelady.
Ray, In the copy of Altgen's photo that you've posted ......It's clear that the man wearing the plaid shirt has his left shoulder dropped low, and the shirt is slipping off his shoulder..... And there is a heavy set man who is wearing a white shirt and tie who is standing in back of the man ( Lee Oswald ?) who is wearing the plaid shirt. IMO The plaid shirt man is Lee Oswald.