I am looking for a series of books, where the two main protagonists are old women, solving crime, much to the dismay of the local police.
If I remember properly, they stumble on their first crime by chance (and I think one of the two is not so enthusiastic about solving crime initially, even pretending to have lost the ability to speak/to become crazy to cool down the enthuasiam of her friend at some point - she start writing weird notes to herself so her friend finds them), then actively look for crime. They are retired, and long time friends or sisters (either widows or never married). One is extremely extroverted and active (and grumpy?), the other introverted and much calmer (it's this one who pretends to go crazy in one of the stories).
I read the series around 2010, but I think it was way older than that. I read it in French, I'm not sure if it has been translated. The series must have worked well enough because I remember reading at least 5 stories with the pair of them.