What I gleaned from reading the letter is that the officer concerned had no intention of either stopping or arresting Mr Bussey. If you're pursuing someone on foot, and you're in a car, catching them is no problem. The only reason for taking a shot at them is if you mean to harm them.
In other words, that cop set out with the intention of shooting a n****r! No more, no less, and the nearest one would do. And given that the sight of an officer was sufficient to set Mr Bussey running, I have no compunction in asserting that this was an attitude all-too-familiar to him. Presumably, had the shot been fatal, it would have 'cleared up' the rape case?
People in Britain tend to crow about our 'unarmed' police, but in this instance it is clear that having the weapon was not a deciding factor. It was the officer's attitude and, as you indicate, that is where reform must take place. Adding an extra layer of bureaucracy in the name of 'accountability' will fix nothing except a few lawyer's mortgage payments.
By the way, from where I'm sitting, a hundred years ago is yesterday.