MB wasn't shot as he was running away.
That's why there were no bullet wounds in his back.
... Or left arm.
Even if you discount the autopsy reports about all the shots coming from the front, and trust the "assistant's" attempt to say one "could have been shot from the back" you would have to believe that officer Wilson had a real grudge against MB's right arm.
Because MB's right arm was on the officer's right as MB was running away, then it was on his left when MB turned around and faced him.
I believe most in the eye-witness report of the guy who didn't know he was being recorded. He said MB turned around and went after the officer even though the officer was shooting.
As for any shots that were fired toward MB while he was running away, those could have been warning shots (doubtful), or just misses (likely), but they would be justified because they fall under the Fleeing Felon rule, as cited here ad nauseum.
Even if the chief was lying when he said that Wilson realized after the initial stop that they fit the description of the BOLO, and didn't know that MB had committed a felony then, he knew without any doubt that MB committed a very serious felony at the car.
I believe he had good reason to and did (as his friend reported) think MB was acting crazy "on something" to do all MB did, and considered MB to be a danger not only to himself, but anyone else who got in his way.