Abu Agila Masud has become only the third person to face charges over the bombing of Pan Am Flight 103 on December 21, 1988.
The Boeing 747 jumbo jet exploded over Lockerbie, Scotland at 7.03pm local time, 38 minutes after taking off from London, killing all 259 people on board and 11 in the town below.
The arrest of Mr Masud, the alleged bomb maker, continues the long quest for justice for the victims and their families. These are the key developments in the investigation to find those responsible, and related developments.
November 1991: Criminal charges are filed against two Libyans, Abdelbaset Al Megrahi, and Lamen Khalifa Fhimah, in Scotland and the US.
1999: Libya hands the two suspects over to face trial.
May 2000: The trial begins in a specially established court of three Scottish judges in Camp Zeist, a former US base in the Netherlands.
January 2001: Megrahi is convicted on 270 counts of murder and Mr Fhimah is acquitted.
2003: Libya accepts responsibility for the bombing and agrees to pay compensation of $10 million for each of the 270 people aboard the plane.
2006: The US lifts its designation of Libya as an international sponsor of terrorism, imposed in 1979.
October 2011: Muammar Qaddafi is deposed and killed
2017: The FBI obtains a copy of an interview conducted with a third bombing suspect, Abu Agila Masud. He is believed to be a bomb maker and to have worked for Libyan intelligence, conducting operations abroad, from 1973 to 2011.
March 2020: The FBI finally gets clarification from the Libyan authorities on the interview and learns that it actually took place on September 12, 2012 while Mr Masud was in Libyan custody.
They learn that Mr Masud said he had worked with Megrahi and Mr Fhimah to carry out the Lockerbie bombing.
December 11, 2022: US and Scottish authorities announce that Masud is in custody in the US.
