What Jewish American Mobster was the predecessor of Murder, Inc.? 
The Bugs and Meyer Mob:  It was formed and headed by mobsters Bugsy Siegel and Meyer Lansky during their teenage years shortly after the start of Prohibition. The Bugs and Meyer Mob:  The Bugs and Meyer mob acted as a predecessor to Murder, Inc. Bugsy Siegel: Benjamin "Bugsy" Siegel (February 28, 1906 – June 20, 1947) was a Jewish American mobster.
Bugsy Siegel