Murder, Inc. (or Murder Incorporated) was the name the press gave to organized crime groups in the 1930s through the 1940s that acted as the "enforcement arm" of the American Mafia, the early organized crime groups in New York and elsewhere. The groups were composed of largely Italian-American and Jewish gangsters from the Brooklyn neighborhoods of Brownsville, East New York, and Ocean Hill. Originally headed by Louis "Lepke" Buchalter, and later by Albert "The Mad Hatter" Anastasia, Murder, Inc. was believed to be responsible for between 400 and 1,000 contract killings, until the group was exposed in the early 1940s by a former group member Abe "Kid Twist" Reles. In the trials that followed, many members were convicted and executed, and Abe Reles himself died after falling out of a window. Thomas E. Dewey first came to prominence as a prosecutor of Murder, Inc. and other organized crime cases.