Simple self-defense, until race-baiters and the media got their hands on it.
The race-baiters may even have had a hand in it earlier, because if Trayvon attacked Zimmerman pre-emptively because he thought the “creepy ass cracka” meant him ill, why would he think that? Because of this type of media portrayal, the evil white cop/man that wants to harm you if you are black.
So this guy’s neighborhood has been burglarized off and on and the residents are very concerned for their safety and well-being. Neighbors agree to upkick their vigilance and overall level of awareness to watch out for each other and keep an eye out for suspicious individuals and behavior. It could be considered by an official designation such as “Neighborhood Watch”, but officially labeled or not, it is the purest form of Americans watching out for each other and being good neighbors.
So far so good.
So George Zimmerman sees what he believes is a suspicious individual in suspicious circumstances, and intelligently and responsibly pays attention and calls 9-1-1 to report what he sees to the officials. This gesture is proof positive he was not looking to do anyone harm or break any laws, but rather perform the fundamental responsibility of a neighbor who cares.
Doing nothing illegal or improper, he follows the individual while answering all the questions from the 9-1-1 operator to the best of his ability, keeping an eye on the individual so the authorities can hopefully intercept and determine exactly what is going on.