I finished the book in one sitting and felt as if I’d been set free. So this is how you do it. ... What I learned from George Higgins was to relax, not to be so rigid in trying to make the prose sound like writing, to be more aware of the rhythms of coarse speech and the use of obscenities. Most of all George Higgins showed me how to get into scenes without wasting time, without setting up the scene, where the characters are and what they look like. In other words hook the reader right away. I also realized that criminals can appear to be ordinary people and have some of the same concerns as the rest of us. ... My take on The Friends of Eddie Coyle, for example -- which I have listed a number of times as the best crime novel ever written -- it makes The Maltese Falcon read like Nancy Drew.Coyle was published in 1971. Right around the time Leonard switched from writing westerns, primarily, to writing thrillers.
1970 - The Moonshine War
1970 - Valdez Is Coming
1972 - Forty Lashes Less One
1974 - Mr. Majestyk
1974 - 52 Pick-Up
1976 - Swag (which introduces the character Stick and is therefore a milestone)
In the passage above there's a character named Foley. Elsewhere a key supporting player named Jackie Brown. Male and white, but still.