That's your opinion. Unfortunately, the facts as we know them at this point won't support a conviction. Let's take it out of the context of this particular case. Suppose I'm walking through your neighborhood. YOu think I look suspicious, so you follow me. I decide to run, and you chase me. You catch up to me, and ask what I'm doing. I ask why you chased me.YOu have not produced a weapon, nor have you touched me. Am I allowed, legally, to hit you, even just once? Of course I'm not! You haven't attacked me; you have not committed any crime (merely chasing me is not one); all you have done is ask a question. I may not like it, BUT, if I hit you at that point, and you haven't threatened me, put your hands on me, or produced a weapon of any kind (even if you have one concealed on you), then I'm committing assault and battery, If you hit me then, I have no legal recourse, because I started the fight!
Now, take it a step further. Let's say that when I hit you, I knocked you down. If I then jump on you, and continue to hit you, and I don't stop, you most certainly have the right to try to stop me. What if you can't; how far can you go to get me off of you?
The answer to that, depends on the law in that jurisdiction. Where I live, if you contributed to the situation in any way, Including chasing me, or even not running away from me when I became hostile, you can't pull a weapon (if you have one) and claim self-defense; that's the way the law reads. However, and it's a big HOWEVER, in FL, that is not what the law says.There, you don't have to avoid me, or run from me. So, if I continue to beat you the law says that If you reasonably believe I am not going to stop, and therefore I may seriously hurt you, you have the right to use whatever force is required to make me stop, including lethal force. Unless the state can prove beyond a reasonable doubt that you attacked me in the first place, or that I stopped attacking you after I knocked you on your butt, you can shoot me, claim self-defense, and you'll walk.
Now, would I have done what Zimmerman did? No, when the kid ran, I'd have let him go; I haven't seen him commit any crime, after all. Chasing him is therefore poor judgement; not worth the risk of a confrontation. If a confrontation HAD occurred, I don't think I'd just shoot the kid, either, even if legally justified; the moment I got him off me, assuming I could, I'd have probably simply advised him I had a gun (and showed him, if he did not immediately back off when so informed). If he attempted to renew the attack at that point, THEN I would have shot him.( and THAT clearly IS self-defense).