That was the begin??ning of what inter??views with more than a dozen sources famil??iar with the inves??ti??ga??tion and other infor??ma??tion now avail??able reveal was a sys??tem??atic effort by the Saudis to obstruct any U.S. inves??ti??ga??tion of the bomb??ing and to deceive the United States about who was respon??si??ble for the bombing.