Born in New York City in 1889, Fein grew up in a poor neighborhood on Lower East Side becoming a petty thief and pickpocket as a child.

Soon after his release in 1910 Fein joined "Big" Jack Zelig's organization, soon becoming involved in labor union and extortion of the Garment District.

In 1913 several minor labor slugger gangs formed to break the monopoly held by Fein and rival Joseph Rosenzweig in which a large shootout took place on Grand Street and Forsyth Street lasting several hours, although few were killed, beginning the New York Labor slugger war that would last almost four years.

[1] In 1941, Fein was arrested by detectives in a police raid ordered by District Attorney Thomas E. Dewey during which mobsters Abraham Cohen, John Ferraro and two Dallas businessmen, Herman Fogel and Samuel Klein, were also taken into custody after purchasing a recently stolen garment shipment valued at $10,000.

[2] He and Cohen were named as the ringleaders of a criminal gang that from armed robbery and burglary, took in an estimated $250,000 over a three-year period raiding the city's garment industry.