The questioning will take place in Tunisia, where the suspect, Ali Ani al Harzi, was transferred after he tried to flea Libya to Turkey following the Sept. 11 incident, CNN reported Saturday.
"We are very pleased the Tunisian government is working with American investigators to allow in person access to Ali Ani al Harzi. Under this arrangement the interviews will be under Tunisian supervision and consistent with their sovereignty and meets the needs of our investigative team," U.S. Senators Lindsey Graham and Saxby Chambliss said in a statement Saturday.
"Allowing American investigators in person access will make the interview more meaningful and is a welcome breakthrough in our efforts to find the perpetrators of the Benghazi consulate attacks," they added.
Federal agents are looking at other suspects, though they have declined to say how many are under investigation, an official who spoke on condition of anonymity said.
U.S. Ambassador Christopher Stevens, U.S. Foreign Service Information Management Officer Sean Smith, and two CIA contractors, Tyrone Woods and Glen Doherty, were killed in the attack.