@marramgrass Edgar Allen Poe created detectives before they were a real thing, there were barely constabulary, nothing like modern "police" and no scientific investigation of crimes until late 19th C.
Private investigators existed in early 19th C, and then the fucking Pinkertons turned it into a Union-busting scam.
I don't know any of them have ever been "famous" in real life, that defeats the purpose of private investigation.