The flouting of Prohibition was so blatant that federal agents targeted the city and the Purple Gang for prosecution. According to Robert A. Rockaway’s book on Jewish gangsters, But He Was Good To His Mother, FBI agents dressed as Hasidic Jews attended a service at B’Nai David on the Day of Atonement, hoping some wanted Purple gangsters would show up. The feds’ cover was blown when they stepped outside to smoke cigarettes, which is strictly forbidden on the holiday."