Blood on the ground is evidence. If all the blood is confined to a small area, then he was standing still. If all the blood is on the ground spread out over 25-30 feet, and the drop patterns indicate Brown was moving toward Wilson, and you have a recording of the shots (was it determined that the audio was real?) - with the last shot being to the top of the head at 4 feet while Brown was going toward Wilson, then the physical evidence clearly indicates the speed at which Brown was going toward Wilson.
Imho, if he had fought Wilson at the car and attempted to get the gun, and was shot at the car (at which point, blood drops will provide a wonderful witness as to his following actions), then I don't care if his hands were up - if he was approaching Wilson, then he got what he deserved.
And, remember, he was shot how many times - and managed to close the distance to 4 feet??? (per a witness quoted in the story above) Had Wilson waited until he closed half the distance before shooting, then Brown would have been able to engage him again (and with fewer wounds).
Thus, there could be plenty of evidence that Wilson was within his right to legally shoot. The prosecutor's choices were: railroad Wilson, state right off the bat that there isn't any legitimate evidence that he committed a crime, or release it ALL to the jury who would have the opportunity to determine whose testimony was complete rubbish, and whose testimony was valid, based on the physical evidence.