The Lerouge Case

A widow is strangled in her cottage at La Jonchère, and an old amateur named Tabaret works out the murderer's height, age, habits and profession from the room in an afternoon — and is wrong. Gaboriau published this in 1866, the first true detective novel in French; Lecoq is a junior man in it, and the point of the book is that a brilliant deduction from physical evidence can convict an innocent man.