Born in New York City, Kastel became a stockbroker and involved himself in fraudulent stock sales through "bucket shop" rackets. In 1921, he led the brokerage firm of Dillon & Company into bankruptcy while writing numerous large checks from drained company accounts. When the company failed, it had about $3,000 in assets and debts to customers in excess of half a million dollars. An investigation followed in 1922, and Kastel disappeared. He turned up in San Francisco and was brought east to stand trial. After delays and two unsuccessful trials, Kastel was convicted April 17, 1926, of fraudulent use of the mails. He was sentenced to serve three years in federal prison but was released on $20,000 bail pending appeals.