Who is your favorite crime fighter, in reality, no fictional characters

A crime fighter here can also be an exceptional true crime author, someone like Ann Rule. Only 2 others i am well aware of -- John Walsh and John E. Douglas. So in splendiforous audiobook format i'll soon be needing new names, either i get help here or somewhere else, the answers and the clues are all over the place, and the hunt is just as good as the dinner.