In my honest opinion, there are only two people who know what actually happened. One of them is no longer here, and we may never hear from the other what really happened. However, there was a witness who described what he saw, and the police officers story doesn't add up to the witness account.
I think there is enough evidence that eventually when the state prosecutor gets the case then it will all come out. Because there were multiple witnesses and this was in broad daylight I think it will be easier to tell what happened then in the George Zimmerman Trayvon Martin case.
There is already a voluminous amount of conflicting information regarding the events surrounding the shooting, and clarity into what really happened seems very scarce. Both sides will be constantly issuing self-serving versions of the events and given those conflicting accounts, it is highly unlikely that the full truth will ever emerge. Also, the perceptions of those who were actually involved in the shooting or who were immediate witnesses could also be skewed depending on relationship to the victim or the officer, political views, etc.
The recollection of what happened in the Michael Brown shooting will differ greatly between individuals. People argue about the intent and purpose of the killing which further complicates the ability to know what took place. Speculation about the event has caused people to be inclined to think a certain way regardless of what actually happened. Even if the truth does come out, many people will not accept it as fact.