Anna Katharine Green 
The Leavenworth Case 

The Leavenworth Case (1878), subtitled A Lawyer’s Story, is an American detective novel and the first novel by Anna Katharine Green. Set in New York City, it concerns the murder of a retired merchant, Horatio Leavenworth, in his New York mansion. The novel introduced the detective Ebenezer Gryce, and was influential in the development of the detective novel. In her autobiography, Agatha Christie cited it as an influence on her own fiction.