One of the witnesses there claimed that while Zimmerman did greatly exaggerate how many times his head had been bashed against the ground, (Zimmerman said the number was somewhere around 50 or something when the actual number was 4-12), but that confirms his head was being bashed against the ground. And at the same time, a Captain in the police force claimed that self defense is better to done earlier than later. I'd say thats pretty convincing evidence right there that Zimmerman isn't guilty.