Why Eastern Airlines Flight 980 Was Sabotaged

Five members of Paraguay's Matalan family were on flight 980. US ambassador to Paraguay, Arthur Davis, was also supposed to be on board but his plans changed the last minute and he didn't get on the plane. NTSB gave up so easily after Bud Leppard failed to get to the crash site,. Why did it take Judith Kelly's expedition and being embarrassed in the Today Show to go back? When they did go back, why was it such a fiasco?