Help a fading memory

[ed goldberg]

Hi All,
Someone asked me whether I knew of a book where a detective investigates a crime and realizes that he, himself, committed the murder. My friend believed it might have been a French novel or story.
This sounds familiar to me, but my aging gray matter has failed to resolve this.
Any ideas?
Thanks.

[ed goldberg]

No, it was a question from a friend, and as I am no big fan of Christie I had no idea.

[ed goldberg]

Oooh, I like this one, and the French thing is very funny.
Thanks.