A spokesman for the Justice Department said Abu Agila Masud is expected to make his first court appearance in the U.S. District Court for the District of Columbia, but didn’t say when. The former Libyan intelligence operative is accused of making the explosive device that destroyed a Pan Am jet on Dec. 21, 1988, killing all 259 people on board the Boeing 747 and 11 more on the ground.

The Justice Department in 2020 charged Masud with helping make the bomb. Attorney General William P. Barr said the operation was ordered by the leadership of Libyan intelligence and that Moammar Gaddafi, Libya’s leader at the time, personally thanked Masud for his work.

A spokesman for the Scottish Crown Office said Scottish prosecutors and police, working alongside colleagues from the United States and United Kingdom, “will continue to pursue this investigation.” The office said it would not comment further, citing the ongoing investigation.

In the deadliest terrorist incident on British soil, the attack took down a plane bound from London to New York. Most of the passengers were Americans, including a group of Syracuse University students returning home for the holidays.