Daniel, with reports I meant the literature I've read on that period, like Five Families, Man of Honor (great on the Castellammarese War), Tim Newark's Lucky Luciano, American Mafia etc. etc.

The most common story is that Lucky stayed on the scene, weeping for poor Joe the Boss, saying that he went for 'a long leak' and when he returned, Joe was dead. Newark claims in his book that none of the news reports of the time mention Lucky being there, and that he probably fled after the shooting.