What would be the point of leaking info if that's the case? Not going to stop it from happening, and the trial would make it obvious how innocent the cop was. If what's been leaked so far is true, the last thing people who hate Darren Wilson want is for this to go to open trial. Few people have bothered to figure out a map with the location of the various witnesses and get a grasp of their realistic view of the events, and I have a suspicion a map of the forensic evidence is going to show a picture the "Brown was an innocent" faction do not want to see.
My train of thought is along the lines of someone with a sense of right & wrong might sense (or know) which way the wind is blowing in the GJ and perhaps wants to get as much out as possible before an indictment is handed down.