I don't know about the "may never face charges" assertion. There was another cop in the car- ie. the driver and he also will be sacked if he does not cooperate with the internal investigation. So the driver cop has this muslim partner in the car who goes off the rails and shoots an unarmed woman who has called the cops. I don't immediately see his motive for flushing his entire career down the drain rather than testifying to what some wackjob did if he was not doing anything wrong himself. Or maybe he will say something that is helpful to his partner. I dont know. I just dont buy into the assertion that if the shooter clams up there will be no prosecution. The shooter is well on his way to being prosecuted for something even if it is a plea deal on some lower level of manslaughter if he panicked around some events.
The police chief has already caved and resigned under the pressure, and next in line is the mayor who is facing a recall attempt. Highly unlikely that the shooter will not pay a price. Even if it was an accidental discharge they will get him on some kind of negligent homicide or something.