The US has announced charges against a Libyan suspected of making the bomb that blew up Pan Am Flight 103 over Lockerbie, Scotland, in 1988.
Abu Agila Mohammad Masud has been charged with terrorism-related crimes, Attorney General William Barr said on Monday, 32 years on from the atrocity.
The deadly bomb attack on the Boeing 747 killed 270 people, including 190 American citizens.
Prosecutors will seek the extradition of Masud to stand trial in the US.
The US claims Masud is an ex-Libyan intelligence operative. He allegedly carried out the attack on the orders of late Libyan leader Muammar Gaddafi.
The bombing of the London to New York flight remains the deadliest terrorist incident ever to have taken place in the UK, and the second deadliest air attack in US history.
Eleven people on the ground in Scotland were also killed. The victims included 35 study abroad US students who were returning home for Christmas.