And by "work with them" I mean "kill and bury them, and then make sure the investigation into their disappearance goes nowhwere." Hat tip to Chechnya, where human rights activist Natalya Estemirova was investigating potential abuses of police loyal to local strongman Ramzan Kadirov. She was rounded up by unknown assailants and murdered, and the case investigating her murder has been stymied.
If that sounds like a Dick Move, I agree fully with you. Have a look at chapter 05 of the Dictator's Handbook for more useful tips on ensuring your investigative types keep their noses pointed in the proper direction.