“Do you feel an uncomfortable heat at the pit of your stomach…and a nasty thumping at the top of your head?… I call it the detective-fever.” - Betteredge [The Moonstone by Wilkie Collins]
An Armchair Detective
Armchair detectives are investigators who do not personally visit a crime scene or interview witnesses; instead, they read about the crime in a newspaper or book or may have it recounted to them by another person. As the armchair detective never sees any of the investigation, they cannot attempt to solve the mystery on the same terms as the police who are directly involved. The phrase ‘Armchair Detective’ possibly originates from a Sherlock Holmes story, The Greek Interpreter, in which Holmes says of his brother Mycroft,
"If the art of the detective began and ended in reasoning from an arm-chair, my brother would be the greatest criminal agent that ever lived."
The earliest example of an armchair detective can be found in the work of Edgar Allan Poe. In The Mystery of Marie Roget, le Chevalier C. Auguste Dupin, who, working wholly from newspaper accounts, arrives at the correct explanation for a young woman's mysterious disappearance.