“
During much of the nineteenth and early twentieth centuries, private detective agencies had filled the vacuum left by decentralized, underfunded, incompetent, and corrupt sheriff and police departments. In literature and in the popular imagination, the all-seeing private eye—the gumshoe, the cinder dick, the sleuthhound, the shadow—displaced the crusading sheriff as the archetype of rough justice.
”
”
David Grann (Killers of the Flower Moon: The Osage Murders and the Birth of the FBI)