Alleged Benghazi attacker appears before US judge

A Libyan accused of involvement in the 2012 attack on a US diplomatic complex in Benghazi that killed four Americans - including the US ambassador - appeared before a federal judge in Washington on Friday.

Mustafa al-Imam, who authorities said is approximately 46 years old, had been days earlier captured in Libya by US commandos.

Dressed in an orange prison suit, he was officially informed via a translator of criminal charges that include killing a person during an attack on a federal facility using a firearm, providing material support to terrorists resulting in death, and use of a firearm in connection with a violent crime. 

The first two counts could carry a potential life prison sentence.

According to the prosecution he was in a group of some 20 armed men who on September 11, 2012 entered the diplomatic complex in Benghazi before setting ablaze a building occupied by US ambassador Chris Stevens.

The ambassador and Sean Smith, a State Department technician, died of smoke inhalation.

The group later fired mortar rounds at a building used by the CIA, killing Glen Doherty and Tyrone Woods, two former members of the Navy SEALs working as contractors.

However, no details on the circumstances of Imam's capture were provided.

Assistant US Attorney Opher Shweiki ruled out the possibility of bail for Imam, citing a "serious risk of flight".  

"He has no ties in the US; he poses a serious danger," Shweiki said. "There is no condition ensuring the defendant will appear in court."

After the approximately 30-minute long hearing concluded US Judge Deborah Robinson ordered Imam remain in custody pending another hearing on Thursday.

'Mastermind'

Meanwhille, the alleged mastermind of the attack, 46-year-old Ahmed Abu Khattala, is already on trial in the US, accused of being a commander of the Ansar al-Sharia militia.

He is accused of being the mastermind of a raid of 20 militants on the US compound in Benghazi, starting a fire that consumed a building killing ambassador Christopher Stevens and a foreign service officers. 

Before that, the militants allegedly killed two US security contractors close to the diplomatic mission, in an event that tainted former Secretary of State Hillary Clinton during her bid to become president.

Khattala has pleaded not guilty to the charges, but the case against him was stalled due to challenges on how he was brought to the US and the evidence obtained during two interrogations.

He was detained on a navy ship for two weeks and underwent five days of interrogation by intelligence agents.

A Washington court ruled against his lawyers' motion to suppress evidence obtained during the 13 days on-board the US naval vessel that they argued violated his rights.

They said intelligence agents interrogated him without informing him of his rights to remain silent, know the charges against him, and have a lawyer present.

His lawyers also argued that the lengthy 13 day trip by ship back to the US was planned from him without legal protections.

Judge Christopher Cooper ruled that in August that fact interrogators repeatedly advised Khattala of his rights to have a lawyer present and to remain silent.

Cooper said he had "knowingly and intelligently" waived these rights.

"Abu Khattala was treated humanely and courteously: He was given breaks every hour or two, and offered snacks and refreshments," the judge said.

"The sheer number of times Abu Khattala waived his Miranda rights - once in writing and twice verbally on each typical interview day - is further evidence of the waivers' voluntariness."

Agencies contributed to this report.