[PW] Need help identifying a mystery

[Nancy Jo Leachman]

The author is British, as is the series. They are older books, pre-1970 & maybe considerably older.
Does anyone recognize this plot? 
The mailman becomes suspicious when the last 3 days milk is still on the stoop. The local bobby goes in and find the body of an elderly woman. The home is slovenly -- in bad repair and dirty.  The woman was found strangled by a wire and hanging from a hook on the wall. Higher ranks are called in.
No one seems to have known her well, she kept to herself. At the beginning, all the cops wonder who would commit such as horrid crime against a poor old woman. By the end of the book, the same cops are glad she's gone as she was a Nazi and guilty of heinous war crimes.
Does this sound familiar to anyone?  Thanks.
 
 
Nancy Jo Leachman
Head of Reference
Salina Public Library
301 W. Elm
Salina, KS 67401
 
785 825-4624