Washington ( CNN ) -- Federal authorities filed 17 new charges against Ahmed Abu Khatallah , alleging that he was the ringleader of twin 2012 attacks on U.S. diplomatic and CIA compounds in Benghazi that killed four Americans . A new indictment against Khatallah , 43 , provides new details of the attack and what federal prosecutors say was his role in leading 20 armed men in the attacks carried out over more than seven hours . Previously , prosecutors charged him with a single count of providing material support to terrorists . According to the indictment , Khatallah conspired with others `` on or before Sept. 11 , 2012 '' to attack the U.S. diplomatic post . `` He believed the facility was being used to collect intelligence , that he viewed the U.S. intelligence actions in Benghazi as illegal , '' the document said . `` These additional charges reflect Ahmed Abu Khattalah 's integral role in the attack on U.S. facilities in Benghazi , which led to the deaths of four brave Americans , '' said Attorney General Eric Holder . The indictment does n't say how much planning was involved , and does n't account for the possibility that the attack coincided with other attacks elsewhere in the Muslim world that targeted U.S. diplomatic facilities . Republican critics have said the Obama administration failed to take sufficient measures to prevent the attacks . They also criticize officials for initially portraying the terrorist rampage as spinning out from street protests blamed on an anti-Islam movie produced in the United States . Khatallah has pleaded not guilty to one count of providing material support to terrorists and will remain jailed until his trial , a federal magistrate ruled in July . He will be arraigned on the new charges on October 20 . Ten of those charges , including murder , could carry the death penalty . Authorities contend that Khatallah is a senior leader of Ansar al Sharia , whose members were among several militias that participated in the two-pronged armed assault . Khatallah remained free for more than a year after the attacks , doing interviews with CNN and other media , prompting criticism of the Obama administration over how long it was taking to arrest the alleged attackers . He was arrested in a military raid in Libya in June and charged in federal court in Washington , D.C. , mere yards away from Capitol buildings where he has become the center of political controversy . Assistant Attorney General for national security John Carlin said in a statement Tuesday that the case `` highlights our resolve to find and hold terrorists accountable wherever they may hide . '' Prosecutors say the attack in Benghazi began around 9:45 p.m. with Khatallah and about 20 armed men attacking the main gate of the diplomatic mission . They set fire to buildings and Khatallah and others allegedly turned away emergency responders . Ambassador Christopher Stevens and Sean Patrick Smith , a mission employee , perished from wounds suffered in that attack . The attackers retreated briefly around 10:15 p.m. , according to the indictment , and then an hour later launched another attack on the mission 's southern gate . They used assault rifles , rocket propelled grenades and other explosives . The attackers plundered what they could from the compound , then shortly after midnight , the indictment says Khatallah and others retreated to a camp operated by Ansar al Sharia . Khatallah then led the attacks on the CIA annex beginning at 12:30 a.m. and again at 5:15 a.m. , according to the indictment . Tyrone Woods and Glen Doherty , security officers at the CIA annex , were killed . At a July hearing , defense lawyers contended the Justice Department has n't provided evidence to support the case .
Grand jury hands down 17 more charges against the militant . Ahmed Abu Omar was captured in Libya and brought to the U.S . He has pleaded not guilty to a charge of providing weapons to terrorists .