The real Mr Klein

This may have been well known at the time "Mr Klein" was made, but I just saw something interesting while seeing "The Sorrow and the Pity" (magnificent 1970 documentary about French life during German occupation in WW2). There was an interview with a shopkeeper called Mr Klein, who was not Jewish but Catholic. He was, however, so worried about being mistaken for a Jew that he took out an ad in the local paper confirming that he was a " true Frenchman". Could this little story have been the inspiration for the 1976 film "Mr Klein"?