Guys, the American Mafia took its structure and hierarchy from its Sicilian antecedents. Jewish mobs were neighborhood-based: There was a boss, a few trusted associates (often blood relatives or close friends from childhood), and the rest were associates. Frequently, the associates plied their own rackets, but could be called on by the boss at a moment's notice. Lepke's Murder Inc. was a loosely organized bunch of thugs in Brooklyn who'd been into shakedowns, bootlegging, gambling, etc. Lepke brilliantly put them on salary, rather than paying them per hit. That way, they were free to continue their rackets but were on call to Lepke, exclusively. Had he paid them per hit, he'd have put himself in a bidding war with other gangsters that he could lose at any time,

After Prohibition, most Jewish mobs dispersed into "legitimate" rackets. Lansky, Siegel,Dalitz and others concentrated on legalized and semi-legalized gambling in the US and Cuba. There was no longer a need to keep together a large army of workers and muscle. Murder Inc. was busted up in 1940-41 and Lepke eventually went to the chair.

Barrett, see my post above about the so-called "Jewish" Russian Mafia.