Ariel Zeitoun, Laurence Siari and Daniel Saint-Hamont started working on the film in 2003. They had to rely mostly on their own research through news articles, television reports and conversations with suspected "Gang des postiches" member André Bellaiche, as no book about the gang had been written at that point.
While the film changes the character names from the real life "Gang des postiches", most characters are in fact based on actual people, with the exception of Gilles Lellouche's character, meant to be a composite of several police officers having worked on the case.