He didn't see the faces but unless they swapped clothes and skin tone then the only actually eyewitness and all the physical evidence points Martin being on top and hitting Zimmerman. Martin had no injuries consistent with rolling around on a sidewalk or being struck. From the time Zimmerman got out of his car until the fighting started was four minutes and martin was a thirty second walk away from his home. if he had wanted to get home he would and could have done so.
I think Zimmerman is an idiot and I would never want him walking around armed in my neighborhood. I don't Zimmerman's story is 100% correct and I base my opinion on what I know of the facts. The is no evidence of Zimmerman reporting people as suspicious just for black so reason to do so now. There is no physical or eyewitness evidence to support that Zimmerman ever struck Martin while there is both for Martin having struck Zimmerman. Scared teenagers close to home flee much more often than the turn and fight so it is very unlikely Martin acted out of fear.
There is some white guy who shot a black teenagers at gas station and is trying to use a stand your ground defense. From the evidence I have seen if I had to bet more 401K I would he is guilty of murder. New evidence could change my opinion on either case.
I am not even a big supporter of the stand your ground law I am just opposed to putting a man on trial based other people's world view instead of the actual evidence.