Green is credited with shaping detective fiction into its classic form, and developing the series detective. Her main character was detective Ebenezer Gryce of the New York Metropolitan Police Force, but in three novels he is assisted by the nosy society spinster Amelia Butterworth, the prototype for Miss Marple, Miss Silver and other creations. She also invented the 'girl detective': in the character of Violet Strange, a debutante with a secret life as a sleuth. Indeed, as Journalist Kathy Hickman writes, Green "stamped the mystery genre with the distinctive features that would influence Writers from Agatha Christie and Conan Doyle to contemporary authors of suspenseful "whodunits". In addition to creating elderly spinster and young female sleuths, Green's innovative plot devices included dead bodies in libraries, newspaper clippings as "clews", the coroner's inquest, and expert witnesses. Yale Law School once used her books to demonstrate how damaging it can be to rely on circumstantial evidence. Written in 1878, her first book, The Leavenworth Case: A Lawyer's Story, sparked a debate in the Pennsylvania State Senate over whether the book could "really have been written by a woman".