http://www.freerepublic.com/focus/f-news/2862676/posts?page=30#30
Read page 3 of the linked report...has some details regarding injuries Zimmerman sustained.
The fact that Zimmerman was bleeding just means that he was in a fight...it says nothing about who started it.
How many fights have you witnessed where the guy who started it ended up taking a beating? I've seen plenty.
Now, if you have an actual LEO doc or tape that has a witness saying that they saw Martin attack Zimmerman why not link to it?