Libyan sources have identified Ahmed Abu Khattala, a Benghazi-based Islamist, as having led the attack on the consulate.
Mr. Abu Khattala, who has acknowledged being at the consulate at the time of the attack, has not been arrested. He has been linked to Ansar al-Shariah, an Islamist group that U.S. intelligence officials suspect was behind the attack.
Mr. Abu Khattala escaped an assassination attempt Sunday, when a bomb exploded as two men tried to plant it under his car in Benghazi. One of the would-be assassins was killed in the blast.
The investigation into the consulate attack has made little headway because of Libya’s weak central government and militias that have taken the law into their own hands.