> I mean nobody is expected to investigate their own group. That is why things like judges/courts, prosecutors, civil/town/city observation groups and federal agencies are there.

Maybe we need a setup where local cops are investigated by the FBI, the FBI and CIA are investigated by DoD's Navy NCIS or Army CID, DoD is investigated by Homeland Security or Treasury, and Homeland Security is investigated by local cops. It's hard to collude around that big a loop.