Armchair detective

Armchair Detective is a term used for a fictional investigator who does not himself (or herself) visit the crime scene or interview witnesses; instead, he or she either reads the story of the crime in a newspaper, or has it recounted to him by another person. The first example of an armchair detective was Baroness Orczy's Old Man in the Corner, who sits in a restaurant and talks to an acquaintance about such cases, almost always finishing by revealing that he has solved the crime.

However, Sherlock Holmes' older brother Mycroft, who appears in some of the stories by Arthur Conan Doyle, may pre-date Orczy; Mycroft's habit, according to Sherlock, is to deduce solutions to crime from his chair at the fictional Diogenes Club.

The term is sometimes used in a wider sense for detectives who send someone else out to do the leg work for them; Nero Wolfe is a primary example. However, some may argue that the essential characteristic of the armchair detective is that neither he/she, nor the reader, actually sees any of the investigation going on, so that complete fair play is ensured.