BENGHAZI, LIBYA - Witnesses provide a chronology for the Sept. 11 attack on the U.S. consulate in Benghazi that differs in significant ways from timelines released in Washington, raising more questions about how the assault unfolded and the speed with which Americans at a nearby CIA annex responded to calls for help from the consulate.

The versions of the attack told in Benghazi indicate that the last visitor who met with Ambassador Chris Stevens, who died in the assault, departed at least 45 minutes earlier than officials in Washington have said. Witnesses also suggest that the attack may have begun as much as 15 minutes earlier than previously reported.

In addition, witnesses said there was no indication that anyone in the U.S. compound knew that protests had broken out in neighboring Egypt over an inflammatory film about the prophet Mohammed that was produced in the United States.

The differences in the timelines could mean that CIA officers stationed in a compound just 1.2 miles away may have waited as long as 40 minutes before setting out to assist the besieged consulate and might not have arrived until more than an hour after the attack began. The CIA's timeline says help was dispatched after 25 minutes and that it took the rescue squad 25 minutes to arrive.

At a minimum, the witness accounts suggest that after two months, the U.S. government still may not know the basic sequence of events and when key moments in the assault occurred.

Visit by Turkish diplomat

On the evening of Sept. 11, Stevens met with the Turkish consul in Benghazi, Ali Sait Akin. While State Department officials said Stevens escorted the Turkish consul out of the compound at 8:30 p.m., a guard at the compound and an official familiar with the meeting said Akin left at 7:45 p.m.

A security guard employed by a British contracting company said he distinctly remembered the time of the meeting because about a half-hour before Akin was scheduled to meet with Stevens, the ambassador approached and asked what security measures were needed to allow the Turkish consul to enter. Stevens addressed the guard in Arabic and told him Akin would arrive at 6:30 p.m. for an hourlong meeting.

As the guard and Stevens spoke, the protests in Cairo had been going on for nearly two hours. Stevens didn't mention the film to the guard, and no one from the compound warned the guard about possible protests, the guard said.

Akin arrived on time and the men met for an hour, the guard said. After the meeting, Stevens and Akin chatted for about 15 minutes as they strolled around the compound, and Akin left at 7:45 p.m.

State Department officials have said the attack started at 9:40 p.m., a time that agrees with the CIA timeline. A Pentagon account said the assault started at 9:42 p.m.

One guard, however, who was at the main gate, placed the assault's beginning at 9:25 p.m. He said a colleague about 25 yards away had alerted him that attackers were approaching. The guard said he saw the attackers and then hit the alarm to alert the compound.