I would have no problem with a citizen review board that maybe works in concert with internal affairs or whatever department is charged with investigating allegations of excessive force/abuse of authority. Whether it is well founded or not, the perception is that when an officer does wrong, others will circle the wagons to protect that officer from outsiders, even if they too believe he did wrong. That perception may be completely unfounded and I don't intend to start a debate over whether there is merit to it or not, but I think there is certainly a segment of society that views it this way. To me, those are concerns over transparency and accountability and a citizen review board that possibly works in concert with an internal affairs investigation could address those issues. My personal belief is that in a majority of the cases, you get the same result or outcome but it will place more confidence in those reviews.
I know some question for the need as that is the purpose of a grand jury, and while that is true with regard to whether or not to refer a case for criminal charges, I think the scope of such a review can be/should be broader than simply determining if criminal charges are warranted. Other issues, such as should any internal action be taken (fire? suspend w/pay? suspend w/o pay? reprimand? no action at all?) can also be addressed. As to this specific case...such a review board would obviously play little or no role in determining if criminal charges should be brought but not every case is referred to the prosecuting attorney's office so quickly.