Have you listened to Zimmerman's OWN 911 calls?
I did.
Let's just assume for the sake of argument that Zimmerman was following Marting "for several minutes" -- which, btw, transcripts indicate he didn't -- is Martin allowed to turn and assault Zimmerman?
If Martin continues to beat Zimmerman while he is on the ground calling for help would that not be the illegitimate use of force in just about any circumstance? Is banging someone's head on the ground potentially life threatening? Is not Zimmerman allowed to defend himself?
If the latest info turns out to be accurate -- which is not a certainty, I'll grant -- then Zimmerman acted in self-defense and Martin's death can only be blamed on Martin.