A courtroom sketch shows Ahmed Abu Khattala, the suspected leader of the 2012 terror attack against a U.S. diplomatic facility in Benghazi, Libya, being arraigned in Washington on June 28. (William Hennessy/European Pressphoto Agency)

Federal prosecutors said Tuesday that they expect to file new charges against a suspected ringleader of the 2012 deadly attacks in Benghazi, Libya.

Ahmed Abu Khattala, who has pleaded not guilty to a conspiracy charge, appeared in federal court Tuesday in Washington for a brief status hearing in the politically charged terrorism case.

Assistant U.S. Attorney Michael DiLorenzo said the government has begun to share with defense attorneys a “large amount” of classified material gathered through hundreds of overseas FBI interviews.

Abu Khattala, a senior leader of the Benghazi-based Ansar al-
Sharia, a jihadist militia, was seized June 15 in Benghazi during a raid by U.S. Special Operations forces. He is the only suspect to be apprehended in the attacks on U.S. outposts that resulted in the death of Ambassador J. Christopher Stevens and three other Americans.

Abu Khattala, who the government estimates is 43, was questioned aboard a U.S. Navy warship for days before being transferred by helicopter to the Washington area.

Ahmed Abu Khattala (AP)

Federal prosecutors have said in court papers that Abu Khattala was “motivated by his extremist ideology” to organize the attacks at a U.S. diplomatic mission and a nearby CIA annex. Ansar al-
Sharia holds anti-Western views, and prosecutors said Abu Khattala “voiced concern and opposition to the presence of an American facility in Benghazi” in the days before the Sept. 11, 2012, attacks.

After the first attack, prosecutors said, Abu Khattala and other armed men looted the compound and prepared for a second attack. Prosecutors said in court last week that the government had provided “some very critical video clips” to the defense team.

With witness interviews and physical evidence gathered overseas, some of which will need to be translated into English, U.S. District Judge Christopher “Casey” Cooper agreed that Abu Khattala’s is an “unusual, complex case,” and he gave the parties more time than usual to determine how to proceed.

Abu Khattala’s attorneys declined to comment after the hearing, saying that much of the material provided to the defense team so far is classified.

The defendant, who is being held in the Alexandria, Va., detention center, listened to the courtroom discussion through a translator but did not speak during the hearing. Abu Khattala was initially charged in a three-count criminal complaint unsealed in June, and he was indicted late last month by a federal grand jury on a single conspiracy charge.

DiLorenzo told the judge that the government could seek a superseding indictment before the next status hearing scheduled for Sept. 9.

Sari Horwitz and Rachel Weiner contributed to this report.