About the same time, according to the timeline, a team of about six CIA security officers and two U.S. military officers landed at Benghazi airport on a flight from Tripoli and began negotiating for transportation into the city.

After learning that Stevens was missing and that the initial attack on the annex had ended, the second team decided to concentrate on finding the ambassador.

“Still pre-dawn timeframe, that team at the airport finally manages to secure transportation and armed escort and – having learned that the ambassador was almost certainly dead and that the security situation at the hospital was uncertain – heads to the annex to assist with the evacuation,” the timeline said.

Backed by Libyan security men, the second team arrived at the CIA annex at 5:15 a.m., just before mortar rounds began hitting the building in a barrage that lasted 11 minutes. One round claimed the lives of Wood and Doherty.

A heavily armed Libyan military unit arrived less than an hour later and helped escort the U.S. personnel to the airport for a U.S. military evacuation flight.

“At every level in the chain of command, from the senior officers in Libya to the most senior officials in Washington, everyone was fully engaged in trying to provide whatever help they could. There was no second guessing those decisions being made on the ground, by people at every U.S. organization that could play a role in assisting those in danger,” said the senior U.S. intelligence official.

In a related development, Foreign Policy magazine on Thursday published draft memos recovered by its reporters from the ruins of the consulate that said that the compound had been under surveillance the day of the attack by a member of the Libyan police assigned to protecting the mission.

“Early this morning at 0643, one of our diligent guards made a troubling report. Near our main gate, a member of the police force was seen in the upper level of a building across from our compound,” said one memo, which was dated Sept. 11 and was intended for the local police chief, according to a handwritten notation at the top. “It is reported that this person was photographing the inside of the U.S. Special Mission.”

“We submit this report to you with the hopes that an official inquiry can be made into this incident and that the U.S. Mission may receive the full support of the Benghazi police,” it continued.

A second draft memo was marked in handwriting for Mohamed Obeidi, the head of the Ministry of Foreign Affairs’ Benghazi office. It contained the same information as the first draft memo, but began with a complaint that a U.S. request for additional police to guard the mission during Stevens’ stay had gone unheeded.

Rep. Darrell Issa, R-Calif., the chairman of the House Committee on Oversight and Government Reform, and Rep. Jason Chaffetz, a subcommittee chairman, wrote to Secretary of State Hillary Clinton asking for any documents or emails that reflected the information in the draft memos as part of a panel investigation into the attack.

“The documents paint a disturbing picture indicating that elements of the Libyan government might have been complicit in the . . . attack on the compound and the murder of four Americans,” wrote the pair.

The congressmen, who have led charges that the administration has suppressed information about the incident, said the documents “support a growing body of evidence indicating that the Obama administration has tried to withhold pertinent facts . . . from Congress and the American people.”