ots of the police procedural have been traced to at least the mid-1880s. Wilkie Collins's novel The Moonstone (1868), a tale of a Scotl

and Yard detective investigating the theft of a valuable diamond, has been described as perhaps the earliest clear example of the ge

nre. As detective fiction rose to worldwide popularity in the late 19th century and early 20th century, many of the pioneering and most popular char

acters, at least in the English-speaking world, were private investigators or amateurs. See C. Auguste Dupin, Sherlock Holmes, Sam Spade, Miss Marple and others. Hercule Poirot was described as a veteran of the Belgian police, but as a protagonist he worked independently. Only after World War II would police procedural fiction rival the popularity of PIs or amateur sleuths. Lawrence Treat's 1945 novel V as in Victim is often cited as the first police procedural, by Anthony Boucher (mystery critic for the New York Times Book Review) among others. Another early example is Hillary Waugh's Last Seen Wearing... 1952. Even earlier examples from the 20th century, predating Treat, include the novels Vultures in the Dark, 1925, and The Borrowed Shield, 1925, by Richard Enright, ret