A Libyan man has denied he was involved in a 2012 attack on the US consulate in Benghazi, during his first appearance before a US court since his capture.
Ahmed Abu Khattalah faced a federal court in Washington on Saturday on criminal charges over the deaths of the US ambassador to Libya and three other Americans from the attack on September 11, 2012.
He had been moved to the US after his capture by US special forces near Benghazi two weeks ago.
His first appearance lasted about 10 minutes, according to the AP news agency.
Khattalah is accused of killing a person during an attack on a federal facility, a crime punishable by death; providing support to attackers resulting in death; and using a firearm in a crime of violence.
US authorities have said they are looking to identify and capture additional co-conspirators.
Khattalah acknowledged in January that he was present during the storming of the US mission in Benghazi. But he denied involvement in the attack, saying he was trying to organise a rescue of trapped people.
In the attack, gunmen fired rocket-propelled grenades and stormed the mission, with many waving the black banners of the armed group, Ansar al-Sharia.
The compound's main building was set ablaze. Ambassador Chris Stevens suffocated to death inside and another American was shot dead. Later in the evening, gunmen attacked a safe house, killing two more Americans.
At the time, several witnesses said they saw Khattalah directing fighters at the site. There is no evidence that he was involved in the later attack on the safe house.
Khattalah's prosecution will be a test of the Obama administration's commitment to put foreign attackers through the US criminal justice system rather than sent them to the US prison in Guantanamo Bay, Cuba.
His is just one of a few cases in which the administration has captured suspects overseas and interrogated them before being brought to a US court to face charges.
Other similar cases include Osama bin Laden's son-in-law, Sulaiman Abu Ghaith, who was arrested in Jordan in March 2013 and handed to US agents. A jury in New York convicted him in March of conspiring to kill Americans.