Yeah, physical evidence may not be able to answer everything, but a drop of common sense can, at least with 99% certainty. Let's see, which is more likely? Wilson attempted to arrest Brown by pulling a man who outweighs him and is larger than him through the window of his vehicle. Or, is it more likely that Brown hit Wilson? Or, maybe Cupid thought the two would make a nice couple, and shot his love arrow at Wilson, but used the wrong type of arrow & it left a bruise on Wilson's face.
Oh, and there's an audio tape of the gun shots. So, you're saying that Brown was shot in the arm while running backwards toward Wilson (blood spatter on ground), then between shots, did a 180 degree turn and faced Wilson while continuing to move toward him.