Du was soon introduced by a friend to , the highest-ranked Chinese detective in the French Concession Police (FCP) and one of Shanghai's most notorious gangsters.
Du's prestige led him to purchase a four-storey, Western-style mansion in the French Concession and have dozens of concubines, four legal wives and six sons, but his meteoric rise as Shanghai's best known mobster only came after Huang Jinrong was arrested in 1924 by the Shanghai Garrison police [REF].