I don't think he looks any more guilty than any other person who has their photo taken. A photo can't ooze guilt.
All I can say is that if I were in the same situation, if I were in fact attacked by a man (let's not kid ourselves...he was 17, outweighed Zimmerman, and was taller...he was the size of an adult and if he were to commit a crime, he'd possibly be tried as one...for all intents and purposes, this wasn't a "child" that the media portrays by showing young pictures of him) and was being beaten with fists, yeah I'd probably pull out my firearm. First as a warning. Then if it continued, I'd probably fire to wound, not kill...but I say that not being in the heat of the moment, being able to think clearly, and being able to rationalize. Who knows what I'd do if I felt my life were in danger? No one was except for these 2 and one of them is dead. Evidence is scant.
I really hope that if it wasn't intentional to kill Trayvon that Zimmerman doesn't get too harsh of a sentence. I think personally that the media is playing this up because of the upcoming election. How many black kids are killed daily in this country on purpose? Why is it that this one is getting so much attention? There's always something that gets used to sway the vote. I think this is no different.