On Monday, the 32nd anniversary of the air disaster, US attorney-general William Barr unveiled the charges against Abu Agila Mohammad Masud.
The United States says Masud admitted to Libyan investigators that he built the explosive device.
The flight had taken off from Heathrow at 6.25 pm on December 21 1988, bound for New York JFK Airport, with 243 passengers and 16 crew on board.
The bomb exploded at 7.02 pm and 11 residents of Lockerbie were killed when the aircraft and debris rained down on the town.
In the following decades, investigators on both sides of the Atlantic attempted to bring those responsible to justice.
The new affidavit explains how two Libyan intelligence agents, Abdel Baset Ali al-Megrahi and Lamen Khalifa Fhimah, were charged in 1991.
A third suspect by the name of ‘Abu Agela Masud’ was also highlighted but investigators were unable to identify the person.
After a trial at Camp Zeist in The Netherlands, Megrahi was convicted on all charges in January 2001 and Fhimah was acquitted.
A joint US-Scottish investigation continued after the trial and, in approximately 2017, the FBI received a copy of an interview conducted by a Libyan law enforcement officer of Masud while he was in Libyan custody.
The affidavit reveals: “In March 2020, FBI agents and officials from Police Scotland interviewed the Libyan law enforcement officer who obtained the statement from Masud.
“This enforcement officer expressed a willingness to testify at a trial if the Libyan Government agreed to make the officer available.”
It also says that Masud admitted building the bomb that brought down Flight 103 and worked with Megrahi and Fhimah to execute the plot.
He further confirmed that the attack was ordered by Libyan intelligence leadership – and that afterwards he was thanked by former Libyan leader Muammar Qadaffi.
The affidavit also states that Masud’s confession is corroborated by evidence gathered by Scottish and American investigators.
In a statement, the attorney general said: “No amount of time or distance will stop the United States, and its partners in Scotland, from pursuing justice in this case.
“From the beginning, the United States and Scotland have been determined to find and hold accountable those who perpetrated the Pan Am 103 attack.
“To the families of those who died in the sky above Lockerbie all those years ago, I know that the small step we take today cannot compensate for the sorrow you feel to this day.
“But I hope that you will find some measure of solace in knowing that we in the United States Government, on behalf of the American people and in partnership with our counterparts in Scotland, have never relented, and will never relent, in the pursuit of justice for you and your loved ones.”
Police Scotland Chief Constable Iain Livingstone described it as ‘a significant development for the families of the victims’ and said: “Since 1988, policing in Scotland has been committed to carrying out the largest terrorist investigation ever undertaken in this country.
“Police Scotland will continue to work closely on this investigation, under the direction of the Crown Office, with our American law enforcement colleagues and other international partners.
“As judicial proceedings continue in Scotland, it would be inappropriate to comment further.”
Meanwhile, Dumfriesshire MP David Mundell said: “I hope the latest developments can lead to families and friends of the victims and everyone else caught up in the events of 1988 being able to find out exactly what did happen in the lead up to the bombing and, in particular, why that Pan Am Flight 103 that night was chosen.”