Three members of the Mara Salvatrucha-13 transnational street gang – one of them an illegal alien from El Salvador – have been hit with federal charges for carrying out a “greenlight,” or murder contract on one of their own who flipped and was working for the FBI, a cold-blooded assassination that was heard live by the informant’s handler.Dennis Anaya Urias, 26, of South Los Angeles, and Grevil Zelaya Santiago, 25, of South Los Angeles, are charged via federal complaint with murder in aid of…..