The president of the Libyan National Council said the attacks not only look premeditated but that they took months to plan.
"It was planned, definitely, it was planned by foreigners, by people who entered the country a few months ago, and they were planning this criminal act since their arrival," President Mohamed Magariaf told Bob Schieffer on "Face the Nation" Sunday.
On the same program, however, America's Ambassador to the U.N., Susan Rice, said that the U.S. has no evidence proving that the attacks in Benghazi were premeditated.
"We do not have information at present that leads us to conclude that this was premeditated or preplanned," Rice told Schiefffer. She said that based on the best information available to date, "spontaneous protests" began outside the Benghazi consulate after demonstrations erupted in Cairo about the anti-Islam movie trailer.
D'Agata, who toured the safe house in Benghazi, said the site shows signs of a well-equipped assault.
"We saw evidence of heavy weapons at the safe house, other mortars and weapons, that take a level of expertise to deploy that accurately," D'Agata said.
That suggestion was raised by Sen. John McCain on "Face the Nation" Sunday, when he disputed Rice's statement, pointing out that those who attacked the U.S. diplomats used heavy weapons and "pretty good tactics - indirect fire, direct fire - and obviously they were successful," adding, "Most people don't bring rocket-propelled grenades and heavy weapons to demonstrations."