Andy Fisher does have a bit of a hard-edge to him, harder than most television shows would have permitted themselves to show in the 1970s. There was one series, however, that did have a bit of an edge to it: Baretta.
The series was supposedly a re-think of Toma, an even harder edged series that was probably too far ahead of its time. (I'm not familiar with it; it wasn't one of my college housemate's favorites when he turned me on to what he considered cheesy must-see TV Re-Runs.) But even softened, the main character had enough class and panache to serve as a role model for many fictional detectives, and I think Andy has some of his DNA as well.