The French Concession in Shanghai from 1940 to 1945, from the isolation period to the fall of Japan, was a mixed bag. The French patrol house was in urgent need of professional criminal investigation talents due to insufficient police force and limited case-handling capabilities. In addition, murders occurred frequently in troubled times. The classes in the concession were clearly divided, with expats, wealthy businessmen, gangsters, ordinary people, and brothel practitioners coexisting. The private market for pornography, gambling, and drugs was rampant, and grievances and entanglements abounded. The focus was only on civilian crimes in the concession.
