I think it looks more and more like people outside any mob family for the reason that every family has been infiltrated by the FBI and other LE for a long time, if it came from there they would have at least one rat feeding them information on who it was, why it was done, and what was behind it. Instead LE seems at a total loss. If is was LCN related one of the other families would have to have heard something and an informant there would have passed along info.