21 December 2014
Last updated at 10:59
Pan Am flight 103 exploded over Lockerbie on 21 December 1988
Relatives of the 270 people who died in the Lockerbie bombing are to attend a memorial service in Washington to mark the 26th anniversary of the tragedy.
Senior Scottish law officers will also be attending the service at the Arlington cemetery on Sunday evening.
The delegation will be led by Lord Advocate Frank Mulholland.
Mr Mulholland said on Saturday he continued to believe Abdelbaset al-Megrahi was guilty of carrying out the bombing.
Megrahi is the only person to have been convicted over the atrocity, which saw Pan Am flight 103 explode over Lockerbie, in the south of Scotland, on 21 December 1988.
He was said by the FBI to have been a Libyan intelligence officer.
But his involvement in the bombing of the flight from London to New York has been called into question by campaigners who believe evidence in the case was manipulated to implicate Libya and divert attention away from Iran and Syria.
The authorities in Scotland have pledged to continue tracking down Megrahi’s accomplices, with investigators visiting Tripoli two years ago to discuss the case with the Libyan authorities after the fall of the Gaddafi regime.
All 259 people on the plane and 11 Lockerbie residents died in the bombing
In a speech at the memorial service, Mr Mulholland will reiterate that the Crown will “never give up the fight to secure justice for the families of those who died” and that “justice has no sell-by date in Scotland”.
And he will also stress that his investigation “remains on the evidence, and not on speculation and supposition”.
Mr Mulholland will add: “The current instability in Libya has meant that some investigative opportunities have required to be reassessed, which I know has been frustrating for family members.
“However our prosecutors and police officers, working with UK government and US colleagues, will continue to pursue this investigation, with the sole aim of bringing those who acted along with Al Megrahi to justice.
“There are other significant investigative opportunities open to us which are not reliant on obtaining evidence from our Libyan colleagues.”
Megrahi was found guilty of mass murder by a Scottish court sitting in the Netherlands in January 2001. His co-accused Al Amin Khalifa Fhimah was acquitted.
Mr Mulholland said on Saturday that no Crown Office investigator or prosecutor had ever raised any concerns about the evidence used in the case.
He added: “Over the years many people have worked on the inquiry and all have been given the same instruction; to carefully review the evidence and work to identify all of those who were involved in the conspiracy to destroy Pan Am flight 103.
“We remain committed to this investigation and our focus remains on the evidence, and not on speculation and supposition.”
Earlier this year, Megrahi’s relatives embarked on a legal bid to clear his name amid claims that his case is the “worst miscarriage of justice in British legal history”.
Megrahi was released on compassionate grounds in 2009 after being given six months to live
He was given a hero’s welcome by the Gaddafi regime when he returned to Libya
Six immediate members of his family joined forces with 24 British relatives of those who died in the atrocity to seek, ultimately, a third appeal against his conviction in the Scottish courts.
They united to submit an application to the Scottish Criminal Cases Review Commission (SCCRC) for a review of the conviction, a move which could see the case referred back to the High Court.
One of those British relatives, Jim Swire, whose 23-year-old daughter Flora died in the bombing, has expressed his disappointment at Mr Mulholland’s latest comments.
Dr Swire told the BBC: “We have so much evidence now that I’m confident that, if we’re granted a fair venue in which to have the evidence re-examined, the evidence against Megrahi would have to be thrown out.
“But that isn’t the point for us. The point for us is that, under European human rights legislation, we have an absolute right to know all that’s known, by our governments, about who murdered our families and why our families were not protected.
“And both those aspects of it are areas in which we don’t feel we’ve been told anything like the truth.”
Megrahi was jailed for life and lost his first appeal against his conviction for murdering the 259 people on the plane and 11 Lockerbie residents in 2002.
An investigation by the SCCRC led to a finding in 2007 of six grounds where it believed a miscarriage of justice may have occurred, paving the way for a second appeal.
But Megrahi dropped that appeal in 2009 before being released from prison by the Scottish government on compassionate grounds in light of his diagnosis with terminal prostate cancer.
He died, still protesting his innocence, in Libya in 2012.