No doubt police should not be above the law and we should call that out.

However this article reads more like hyperbolic slander.

They're leveling some hefty accusations and signing their name on it. It would be monumentally stupid for J.K. Trotter, the author, to say these things without having any proof that holds up in court. If it's false, they would be sued and lose quickly. The data is pretty much all public record combined with standard journalism work.

which part is hyperbolic, and which part is slander?

(remember that a statement has to be false to be slander)