A simple form of The Reveal used to explain why Police Are Useless, and why our otherwise normal characters don't simply ask the police to deal with the dangerous criminals. It turns out the police are the criminals. Generally speaking this trope is intended to rationalize why the main characters don't go to the police with their problems, which tends to be the logical response by normal people to outrageous things like murder plots. This can also be established in the backstory and does not need to be displayed on-screen directly. Examples of The Bad Guys Are Cops include: