Robert Bresson insisted on complete authenticity. Original author André Devigny served as adviser on the film, which was actually shot in the same Montluc prison where he was incarcerated. André Devigny also loaned Robert Bresson the ropes and hooks he had used in his escape.
After seeing the film, Jean-Luc Godard said that Robert Bresson was "to French cinema what Wolfgang Amadeus Mozart is to German music and Fyodor Dostoevsky is to Russian literature".
When the film was shot, the Montluc prison was still an operating prison. The prisoners had to be evacuated to other facilities for two weeks during the shooting of the film on location. The prison was definitively closed in 2009. It is now a memorial.