I think it's obvious there was a physical confrontation. Who engaged initially is up for debate, however. That's really the crux of the case. If Zimmerman headed back to his truck and Martin tracked and attacked him, then the shooting was likely justified. If, on the other hand, Zimmerman didn't really retreat and Martin responded to what he felt was an immediate threat, getting shot in the process, then Zimmerman is guilty. I mean, if I follow you down a dark alley and corner you, are you really the one initiating contact when you hit me?