What nickname did the American gangster Arthur Flegenheimer have?

Dutch Schultz (born Arthur Simon Flegenheimer; August 6, 1902 – October 24, 1935) was a New York City-area Jewish-American mobster of the 1920s and 1930s who made his fortune in organized crime-related activities, including bootlegging and the numbers racket. Weakened by two tax evasion trials led by prosecutor Thomas Dewey, Schultz's rackets were also threatened by fellow mobster Lucky Luciano. In an attempt to avert his conviction, Schultz asked the Commission for permission to kill Dewey, which they refused. When Schultz disobeyed them and made an attempt to kill Dewey, the Commission ordered his murder in 1935.

Shortly before his death, fearing that he would be incarcerated as a result of Dewey's efforts, Schultz commissioned the construction of a special airtight and waterproof safe, into which he placed $7 million in cash and bonds. Schultz and Rosencrantz then drove the safe to an undisclosed location somewhere in upstate New York and buried it. At the time of his death, the safe was still interred; as no evidence existed to indicate that either Schultz or Rosencrantz had ever revealed the location of the safe to anyone, the exact place where the safe was buried died with them. Gangland lore held that Schultz's enemies spent the remainder of their lives searching for the safe. The safe has never been recovered.