Well, as you say, one is too many.
And that's not really something I would write in parentheses - that's something I would highlight in bold with exclamation marks. Until we start seeing bad cops going to jail, this really isn't something that you can fudge over by saying "but not all cops!" Bad police don't have permission to murder people just because there are good police who wouldn't, and it really does keep coming back to that.