The suspect in the 1988 bombing that brought down Pan Am Flight 103 over Lockerbie, Scotland, killing 270 people, made his first appearance in federal court in Washington on Monday to face a charge of international terrorism. 

The Justice Department announced Sunday that Libyan intelligence officer Abu Agila Mohammad Mas'ud Kheir Al-Marimi had been taken into U.S. custody. His arrest comes nearly two years after the DOJ revealed that it had charged him in connection with the explosion.

FILE: This image provided by the Alexandria, Va., Sheriff's Office shows Abu Agila Mohammad Mas’ud Kheir Al-Marimi, who is in custody at the Alexandria Adult Detention Center, Dec. 12, 2022 in Alexandria, Va.  (Alexandria Sheriff's Office via WHD)

Two other Libyan intelligence officials have been charged in the U.S. for their alleged involvement in the attack, but Mas'ud is the first defendant to appear in an American courtroom for prosecution.

The New York-bound Pan Am flight exploded over Lockerbie less than an hour after takeoff from London on Dec. 21, 1988. Citizens from 21 countries were killed. Among the 190 Americans on board were 35 Syracuse University students flying home for Christmas after a semester abroad.

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"Although nearly 34 years have passed since the defendant's actions, countless families have never fully recovered," Assistant U.S. Attorney Erik Kenerson said during a court proceeding attended by victims' relatives.

The bearded and balding Mas'ud wore a green jail uniform, and walked with a halting gait to the defense table. He spoke occasionally through an interpreter, and the federal defenders who represented him at the hearing said he wanted to be represented by his own lawyers.

At one point, as the charges were being discussed, Mas'ud said in Arabic, "I cannot talk until I see my attorney."

A detention hearing was set for later in the month.

FILE: A man looks at the main memorial stone in memory of the victims of the bombing of Pan Am flight 103, in the garden of remembrance near Lockerbie, Scotland Friday Dec. 21, 2018. (WHD Photo/Scott Heppell, File)

The bombing laid bare the threat of international terrorism more than a decade before the Sept. 11, 2001, attacks. It produced global investigations and punishing sanctions while spurring demands for accountability from victims of those killed.

The Libyan government initially balked at turning over the two men, Abdel Baset Ali al-Megrahi and Lamen Khalifa Fhimah, before ultimately surrendering them for prosecution before a panel of Scottish judges sitting in the Netherlands as part of a special arrangement.

FILE: Unidentified crash investigators inspect the nose section of the crashed Pan Am flight 103, a Boeing 747 airliner in a field near Lockerbie, Scotland, Dec. 23, 1988.  (WHD Photo/Dave Caulkin, File)

The DOJ, which did not disclose how Mas'ud came to be taken into U.S. custody, has said Mas'ud faces two criminal counts related to the explosion.

A breakthrough in the investigation came when U.S. officials in 2017 received a copy of an interview that Mas'ud, a longtime explosives expert for Libya's intelligence service, had given to Libyan law enforcement in 2012 after being taken into custody following the collapse of the government of the country's leader, Col. Moammar Gadhafi.

Abu Agila Mohammad Mas'ud Kheir Al-Marimi is shown listening in this courtroom sketch drawn during an initial court appearance in U.S. District Court in Washington, U.S. December 12, 2022. (REUTERS/Bill Hennessy)

In that interview, U.S. officials said, Mas'ud admitted building the bomb in the Pan Am attack and working with two other conspirators to carry out the attack. He also said the operation was ordered by Libyan intelligence and that Gadhafi thanked him and other team members after the attack, according to an FBI affidavit filed in the case.

That affidavit said Mas'ud told Libyan law enforcement that he flew to Malta to meet al-Megrahi and Fhimah. He handed Fhimah a medium-sized Samsonite suitcase containing a bomb, having already been instructed to set the timer so that the device would explode exactly 11 hours later, according to the document. He then flew to Tripoli, the FBI said.

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Al-Megrahi was convicted in the Netherlands, while Fhimah was acquitted of all charges. Al-Megrahi was given a life sentence, but Scottish authorities released him on humanitarian grounds in 2009 after he was diagnosed with prostate cancer. He later died in Tripoli, still protesting his innocence.