I think what happen, is Zimmerman didn't give up on following Trayvon. Zimmerman history in dialing 911, always suggested that these supicious teenagers were gaining access to the community through a back gate. Zimmerman then proceeded to go to that back gate. Zimmerman then approached Trayvon, argument starts, when Trayvon hits Zimmerman knocking him to the ground, causing him to hit the back of his head. In order for this to happen Zimmerman has to be in close proximity to Trayvon, this would suggest that Zimmerman may have tried to detain him. The moment, IMO, Zimmerman decided to follow Trayvon he made himself suspicious to Trayvon. Making him responsible for whatever outcome that occurs, good or bad, because at that point he has already justified his actions to himself. By caring a firearm, Zimmerman determined that he is willing to harm or kill if need be. What is a fact? Is the majority of Americans respond differently to a law enforcement officer in uniform, then one that is not in uniform. So what is the obvious reponse to a stranger, playing cop? Who isn't wearing a security uniform.