I think we can agree that the multiple narratives on this event concur that the struggle took place in the police car while the shooting took place well away from the police car. The struggle, which supposedly justifies the shooting, was over and done when the final shots were fired. And, so far as I know at the moment, no shots were fired inside the police car.
This to me means Brown was running away and that Wilson had control of his firearm when the first shot, subsequent shots, and the last shot were all fired. The autopsy reports (both of them so far) do not mention any tattooing from powder as you'd see with someone who was shot at close range, especially with regards to the shots to the bare arm.
Officer Wilson has some explaining to do. I won't rush to judgment, but I'm just saying that the facts in the story are not exactly lining up with the official narrative.