That's Chicago based. They were actually secretly working for CPD Internal Affairs, and their CO (who knew of their side work for IA, but not who the subject of

That's Chicago based. They were actually secretly working for CPD Internal Affairs, and their CO (who knew of their side work for IA, but not who the subject of the investigation was) leaked it to everyone, which made it nearly impossible for them to actually investigate the particular officer who was suspected of being a local drug kingpin / murderer (convicted much later of a small fraction of the stuff he's alleged to have done). The Intercept ran one of their big series on it. It's definitely an interesting read, but it's lengthy. https://theintercept.com/series/code-of-silence/ https://theintercept.com/series/code-of-silence/