WASHINGTON (AFP) - The suspected ringleader of a deadly attack on the US mission in the Libyan city of Benghazi pleaded not guilty during a brief court appearance on Saturday in federal court.
A federal grand jury indicted Ahmed Abu Khatallah during the rare Saturday session on a single charge of conspiracy to provide material support and resources to terrorists resulting in death, for the attacks that killed US ambassador Chris Stevens and three other Americans two years ago.
Abu Khatallah is due back in court on Wednesday for a detention hearing at 11am, and again on July 8 for a status hearing.
He was flown to Washington by helicopter shortly after sunrise from a US Navy warship where he had been held since his high-profile capture two weeks ago, a law enforcement official told AFP.
ABC News said the suspect, believed to be 43, listened to the court proceedings through an interpreter and raised his right hand.
He spoke only briefly and softly before the judge and almost a dozen lawyers and government officials in the courtroom, according to the television network.
The Justice Department has charged Abu Khattalah with three counts in connection with the attacks that saw gunmen storm the US mission in Benghazi and set it on fire.
A CIA outpost was also targeted in the attacks that shocked Washington and grew into a highly charged political issue.
The US State Department has identified Khatallah as a senior leader of Ansar al-Sharia, a Libyan "terrorist" group responsible for a spate of attacks and assassinations.
US commandos captured Khatallah - who could face the death penalty - earlier this month in a covert raid on Libyan soil.
Special forces, working with FBI agents, carried out the stealth operation to seize Khatallah - whom the US has accused of being the attack ringleader - under cover of darkness and withdrew without losses.
Libya accused Washington of violating its sovereignty.
The raid two weeks ago represented a victory for President Barack Obama, who has faced intense criticism from both fellow Democrats and Republican foes over his administration's handling of the Benghazi assault and its aftermath.
But in one challenge to the case, FBI investigators were only able to visit the crime scenes to collect evidence several weeks after the assault due to high security concerns.
US federal prosecutors have charged Khatallah with murder, carrying a weapon and offering material support to "terrorism."
The charges reflect accounts from Libyan officials and witnesses who have singled out Khatallah as allegedly taking part in the assault that day.
FBI Director James Comey hailed Abu Khatallah's capture as a "major step forward" in the investigation, but stressed that "our work, however, is not over."
"This case remains one of our top priorities and we will continue to pursue all others who participated in this brazen attack on our citizens and our country," he added.
And the Justice Department stressed that it could bring additional charges against Abu Khatallah as the case proceeds during the ongoing investigation.
Khatallah had been seen in public often since and gave an interview to The New York Times last year, striking a defiant tone over a strawberry frappe at a cafe in a luxury hotel in Benghazi.
But US officials have dismissed suggestions that the suspect was "hiding in plain sight" or that the operation to capture him could have been conducted much sooner.
The Benghazi attack raised questions about security at US missions worldwide and has been the subject of fierce political debate. Former secretary of state Hillary Clinton faced hostile questioning before lawmakers over the issue.
Republicans alleged that the White House failed to respond decisively and then tried to hide some facts in the grisly episode.
The Obama administration, in turn, has accused critics of politicising a tragic event and says that it has divulged all the details of the episode.