You could say that the contemporary female detective started with Sue Grafton’s “A” is for Alibi in 1982, featuring the very “hard boiled” Kinsey Millhone. She personifies the feminist anger of the 70’s and 80’s and the author stated she got the idea for the story when imagining killing her husband during her divorce. In the climax of the story, when Kinsey is being pursued by the murderer (who was also her lover), she shoots him and then simply says, “I blew him away.”
Kinsey’s female detective ancestors were considerably less “hard boiled.” English mystery writer Agatha Christy had started with an eccentric male detective, Hercule Poirot in The Mysterious Affair at Styles in 1920. He would continue for an extraordinary fifty-four short stories and thirty-four novels ending in 1975 with Curtain. He would be joined by Miss Marple in 1930. She would appear in a respectable twelve novels and twenty short stories. Miss Marple is the prototype non-threatening, “old maid” detective. She would never calmly shoot someone and then make a flip remark.
The female detective as personified by Kinsey Millhone had her roots in the idea that a woman did not have to be “feminine.” Thus she is a kind of female version of a male detective.
This evolved to where more recently-conceived female detectives are not so “macho.” They can be quite capable and don’t need to turn to a man to rescue them, but have a female’s tastes, interests, and sensitivity. The contemporary, post-Kinsey Millhone (post feminist) female detective also is more likely to find herself in a romantic involvement. This has led to a blurring of boundaries between the mystery fiction genre and another genre traditionally associated with women readers, Romance—see Mystery Romance.