This is my first post and right away I ask for your help.
I remember that in a novel (it could also be a short story, but I do not think) Poirot said that a murderess who did not do and did not say anything after the murder might even beat him.
In practice, Poirot says that are the attempts to conceal evidence and the talking the main problem of a murder.
The piece should be at the beginning of the story, if I remember correctly.
Does anyone remember what book could be?
Thank you so much