It is really not difficult at all. A UPI wire service article really says how the coup takes place. The writer is talking about a reputation. Not proven conduct but rumored, or planted, information about someone or something. Many people, organiztions, or other entities have reputations and many, if not most reputations, are untrue, unfair or inaccurate, and unearned.
Allegations are statements without proof.
The feds are not trying to prove that LAPD is a corrupt organization. All they are alleging is that there is an alleged pattern of improper behavior drawn by some source. No actual proof of improper behavior is necessary showing LAPD is corrupt or is directing its officers to commit unlawful acts. The pattern, though, is the key which unlocks the courtroom door. The feds now simply go to the local politicians, many if not most, who belong to the same national political club that the feds belong to.