CNN has a timeline of events and some account of what Zimmerman told police. If the CNN timeline is accurate, there are cogent reasons to disbelieve Zimmerman's account and I understand why the prosecutor charged him. From the CNN timeline:
“According to an Orlando Sentinel story later confirmed by Sanford police, Zimmerman tells authorities that, after Zimmerman briefly lost track of Martin, the teen approached him. After the two exchange words, Zimmerman says, he reaches for his cell phone, and then Martin punches him in the nose. Zimmerman says Martin pins him to the ground and begins slamming his head into the sidewalk.”
According to the above, Zimmerman's own account is not that he was attacked by surprise as many people suggest. He was actually talking to Martin. That jibes with GF’s account that she heard the two of them talking and Martin asking why Zimmerman was following him. Listen to the GF’s account to police. According to her account, Zimmerman was pursuing Trayvon (also bear in mind, he was doing so with his car).
Zimmerman was still in pursuit (in a car) and found Martin, even after Martin thought he had lost him. According to above, Zimmerman told police Martin approached him. Based on the GF's account to police, that's a lie. Zimmerman pursued him with his car and then exited the vehicle to confront Martin. According to Zimmerman, they exchange words. Zimmerman tells police he went for his cell phone and Martin punches him.
Lets assume for a moment that the above statement from the CNN timeline of the event sequence and Zimmerman's statements is accurate. Zimmerman had a gun on him. Why is it not plausible that Martin thought Zimmerman was going for his gun and struck first before Zimmerman could draw his weapon on him? That’s not an unreasonable reaction since I’m sure Martin rightly assumed he could not outrun a bullet. This guy was following him, the guy is armed, he is not a cop, Martin hasn’t done anything to anybody and is on a public street where he has a right to be, he’s been running from this guy (who’s pursuing him in a car), he's winded, scared and is now confronted by an unknown hostile dude with a gun and all he’s got is ice tea and a bag of skittles to work with.
In that scenario, he’s got a legit fear for his own life. Now, if in fact, Zimmerman is lying (I believe he is based on the GF's account) about how they came into contact, what really happened is that he chased Martin down with his car, then exited his vehicle to confront him.
Many are saying the physical evidence syncs with Zimmerman’s account, namely that Martin's autopsy revealed no wounds on his body other than the fatal gunshot and an abrasion on his finger. But that physical evidence syncs with an alternate interpretation of events as I’ve posited here based on the GF’s statement to police and the CNN timeline and statements to the police by Zimmerman (assuming its accurate). That gets to the heart of the issue of how this encounter got started.
If Trayvon had attacked Zimmerman in some surprise attack as some have posited, then I’d say its a tragic deal, but Zimmerman does not deserve jail. However if what happened is that the armed Zimmerman essentially chased down the unarmed Martin in his car (who has done nothing but walk down the street, committed no criminal behavior or trespass of any kind, he was just there)and then confronted him when the boy decided he was not going to run any more, that situation could have been avoided and the killing that resulted is on Zimmerman.
Assuming the CNN timeline and statements to the authorities attributed to Zimmerman are accurate and if you accept the GF’s account to the police of what she heard (I do), it is Zimmerman’s actions that are the direct cause of this incident. Trayvon did try to leave the area, he was pursued with a car and then confronted by a man with a gun and all he was doing was walking down the street. In that scenario Zimmerman’s injuries make complete sense. Martin was unarmed and fighting for his life against a man armed with a gun who chased him down in a car and whom he had every credible reason to believe was going to shoot him. Sounds like Stand Your Ground in Trayvon's favor all day long to me.