The Flamingo opened on Decemin a driving rainstorm, resulting in a poor reception and technical difficulties, and it soon closed. Siegel assumed control of the project and managed the final stages of construction. Wilkerson's Flamingo Hotel after Wilkerson ran out of funds. Siegel traveled to Las Vegas, Nevada, where he handled and financed some of the original casinos. In 1941, Siegel was tried for the murder of friend and fellow mobster Harry Greenberg, who had turned informant. His time as a mobster during this period was mainly as a hitman and muscle, as he was noted for his prowess with guns and violence. In 1936, he left New York and moved to California.

The Twenty-first Amendment was passed in 1933 repealing Prohibition, and he turned to gambling. and became a bootlegger during American Prohibition. Siegel was one of the founders and leaders of Murder, Inc. Described as handsome and charismatic, he became one of the first front-page celebrity gangsters. Siegel was influential within the Jewish Mob, along with his childhood friend and fellow gangster Meyer Lansky, and he also held significant influence within the Italian-American Mafia and the largely Italian-Jewish National Crime Syndicate.

Benjamin ' Bugsy' Siegel (Febru– June 20, 1947) sometimes known as Ben Siegel, was an American mobster who was a driving force behind the development of the Las Vegas Strip.