A team of U.S. investigators traveled to the eastern Libyan city of Benghazi on Thursday to visit the compound where the U.S. ambassador was killed in an attack last month, Libyan security sources said.
FBI agents were dispatched to Libya after the September 11 assault on the U.S. diplomatic mission and on another facility in which Ambassador Christopher Stevens and three other Americans were killed.
But, until now, the agents apparently have remained in Tripoli.
"An American team has been visiting the compound," one Libyan security source said. Another security source said: "They have been assessing the damage, collecting evidence."
In Washington, U.S. Attorney General Eric Holder suggested the probe had been active despite the weeks-long delay in getting FBI agents to Benghazi.
"You should not assume that all that we could do or have been doing is restricted solely to Benghazi. There are a variety of other places, in-country and outside the country, where relevant things could be done and have been done," Holder said at a press conference.
"This is a matter that's been under active investigation almost since the time of the incident, and I'm satisfied with the progress that we have made," he said.
Separately, the Pentagon on Thursday confirmed the visit of an FBI investigation team to Benghazi, and said U.S. military personnel provided support to the mission.
But a spokesman indicated the FBI team had since departed.
"At the request of the FBI, the department provided logistic and security support to the investigation team in order to conduct work on-site in Benghazi," Pentagon spokesman George Little told reporters. "(Department of Defense) personnel completed that support earlier today and have departed Benghazi along with the investigation team."
In Benghazi, the road leading to the compound's front gate was blocked by vehicles mounted with weapons belonging to the Libyan security forces, a Reuters witness said.
Libyan Deputy Foreign Minister Mohammed Abdel Aziz said on Tuesday that the FBI team would soon be heading to Benghazi but said that Tripoli and Washington had yet to agree on how the two sides would conduct a joint investigation.
U.S. Secretary of State Hillary Clinton on Wednesday vowed every effort would be made to try to piece together a full account of the attack on the U.S. consulate "wherever that leads," but cautioned that it could take time for a complete picture to emerge.
Libyan officials say eight people have so far been arrested in connection with the attack.