(CNN) -- Two Tunisians are being questioned in Turkey in connection with an attack on the U.S. Consulate in the Libyan city of Benghazi that left four dead, a U.S. official with knowledge of the investigation said Friday.
The Tunisians -- who had been on a watch list provided by the United States to Turkish authorities -- were questioned at the request of the United States, according to the official. They entered Turkey this week.
FBI investigators have not talked to the two Tunisians yet, but "that's the hope," the U.S. official said.
The official did not confirm or deny if the suspects entered Turkey using fake passports, as has been reported by Turkish media.
The September 11 consulate attack killed U.S. Ambassador to Libya Chris Stevens and three other Americans. The incident heightened global scrutiny of the North African nation and sparked debate about whether members of President Barack Obama's administration were being forthcoming about the incident.
In the days after the assault, U.S. administration officials offered conflicting assessments on what may have led to the fatal security breach.
Officials initially said the violence erupted spontaneously amid a large protest about a privately made video produced in the United States that mocked the Prophet Mohammed.
But the U.S. intelligence community revised its assessment, saying it believes it was a planned terrorist assault.
The intelligence community now believes it was "a deliberate and organized terrorist assault carried out by extremists" affiliated with or sympathetic to al Qaeda.