Police officers often lie about what can or will be charged for political reasons (or laziness reasons, or some other reason unrelated to what the DA supposedly will or won't do). That is why the parent said it might be propaganda.
I do not think cops are more or less corrupt than the average, but I do believe a corrupt cop has more impact than average. And because of that I do think they need higher standards and more accountability. I do not think they as a group need to be the “them” in the “us vs them” mentality.