As I posted earlier, because of those counterfeit passports, it's hard to know for sure who is or isn't Jewish in the "Russian Mafia" either here, in Russia or in Israel.

The Macdonald story is interesting, and since no one was ever indicted for Siegel's murder, anything's possible. But I'm sceptical that, if Dragna was involved (and he might have been), he'd have chosen an assassin who wasn't inside organized crime--a "civilian." Carbo would have been a logical choice: he was the triggerman in the assassination of Harry (Big Greenie) Greenberg, a dimwit NY thug who sang to the cops and tried to hide out on the Coast. Siegel fingered Greenie for him, and Allie (Tick Tock) Tannenbaum of Murder Inc. was in on it. It'd be logical for Luciano to use Dragna to arrange the Siegel hit, and to send Carbo to him to carry it out.
As you may know, Carbo later became the top guy in the boxing rackets, which made millions for the Mob.