Maigret's Secret: Inspector Maigret, 54 (Unabridged‪)‬

At a dinner party, Maigret recounts an old case in which Adrien Josset is found guilty and executed for the murder of his wife, Christine. As the case develops under the controlling hand of the magistrate, all clues point to Josset's guilt, yet Maigret is left unconvinced following his one interview with him. 

Years after the case, Maigret still doubts the true identity of the murderer.  

This novel has been published in a previous translation as Maigret Has Doubts.