CAIRO (AP) — One of Libya’s rival prime ministers called Tuesday for the release of the former Libyan intelligence officer accused of making the bomb that downed Pan Am Flight 103 over Lockerbie, Scotland, in 1988, killing all onboard, after he surfaced in U.S. custody earlier this week.

American authorities said Abu Agila Mohammad Mas’ud Kheir Al-Marimihad been arrested and would face trial in the United States. On Monday, he appeared in a Washington, D.C., federal court, where he was charged with an act of international terrorism.

“My question directed to the American administration is how…he reached Washington,” Fathi Bashagha, one of Libya’s rival prime ministers, told a local Libyan television channel as he was leaving a meeting of the country’s East-based parliament. “What we think is that he was kidnapped, Of course, this is outside the legal, judicial and legitimacy framework, and this is something I reject and do not recognize. At all.”

Torn by civil war since 2011, Libya is divided between two rival governments, each backed by international patrons and numerous armed militias on the ground. One is based in Tripoli, and the other, headed by Bashagha, is based in Sirte with a parliament in the eastern city of Tobruk. In western Libya, militia groups have amassed great wealth and power from kidnappings and their involvement in the country’s lucrative human trafficking trade.

Bashagha’s comments seemed to suggest that his rival’s government, that of Prime Minister Abdul Hamid Dbeibah, based in Tripoli, was somehow complicit in the operation to extract Mas’ud.

Mas’ud’s extradition is a milestone in the decades-old investigation into the attack that killed 259 people in the air and 11 on the ground. American authorities in December 2020 announced charges against Mas’ud, who was in Libyan custody at the time. Though he is the third Libyan intelligence official charged in the U.S. in connection with the attack, he is the first 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 different countries were killed. Among the 190 Americans on board were 35 Syracuse University students flying home for Christmas after a semester abroad.

American authorities in December 2020 announced charges against Mas’ud, who was in Libyan custody at the time. A breakthrough in the Justice Department’s 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.

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 plan. He also said the operation was ordered by Libyan intelligence and that Gadhafi thanked him and other members of the team after the attack, according to an FBI affidavit.

U.S. officials did not say how Mas’ud came to be taken into U.S. custody, but late last month local Libyan media reported that Mas’ud had been kidnapped by armed men on Nov. 16 from his residence in Tripoli, the capital. That reporting cited a family statement that accused Tripoli authorities of being silent on the abduction. It remains unclear under what circumstances Mas’ud was released from prison since the 2020 announcement.