Khatallah walked into a courtroom in Washington D.C. wearing a black sweatshirt, black sweatpants and slip on plastic sandals. He spoke softly when asked a question by the judge.
The Libyan militant replied yes when he was asked to swear to tell the truth. He also answered no when asked if he had a problem understanding what was taking place.
Khatallah was wearing headphones so he could listen to an instant translation of the entire hearing.
His lawyer, who was appointed by the court, entered the plea of not guilty to a count of giving material support to terrorist.
The presiding judge ordered that Khatallah remain in detention. He was led away and taken to an Alexandria, Virginia facility following his hearing.
The current indictment against the Libyan militant was given over under seal Thursday and made public on Saturday.
A grand jury indicted Khatallah on conspiracy to provide resources and material support to terrorists with the knowledge and intend that these would in turn be used to prepare and carry out a killing via an attack on a U.S. federal facility.
Khatallah flew to Washington on a helicopter just prior to sunrise Saturday. The helicopter picked him up on a navy warship the home of the Libyan militant since he was captured just over two weeks ago.
Prosecutors accuse Khatallah of taking part in the attack in Libya on September 11, 2012 that led to the killing of Chris Stevens the former U.S. Ambassador to Libya, Sean Smith an information officer and Glen Doherty and Tyrone Woods two former SEALs with the U.S. Navy.
Stevens’ death mark the first time a U.S. Ambassador had been killed while in the line of duty 33 years.
Special Forces captured the Libyan militant during a raid at night between June 15 and 16. His arrest marked the first breakthrough in the Benghazi attacks investigation.