Start with the Inspector Wexford novels. I think From Doon with Death is the first one. It was published in the early 1960s so if you want cell phones, data bases, and the latest forensic techniques, you will be disappointed. Reg Wexford is one of my favorite series detectives. He's got common sense and is never cynical or callous. His sidekick Burden, however, is the one that does the most changing from novel to novel. The books she publishes under the Barbara Vine pen-name are more gothic with lots of psychological torment and edgy thrills. There's next to no violence in her stories but they are very scary.
The first five Wexford ones are: From Doon with Death (1964), Wolf to the Slaugher (1967), A New Lease of Death (1969), The Best Man to Die (1969), and A Guilty Thing Surprised (1970).