Glasgow, Scotland - The dark spectre of the Lockerbie bombing resurfaced again last week, after more than three decades of enduring controversy.

The Pam Am flight 103 disaster in the Scottish town of Lockerbie in December 1988 saw all 259 passengers and crew on board, as well as 11 people on the ground, die as the plane crashed following a mid-air bombing, turning a sleepy rural setting, just 20 miles (32km) north of the border with England, into "hell on earth".

But on March 11, the Scottish Criminal Cases Review Commission (SCCRC) stirred the ghosts of a painful past when it announced that the conviction of Abdelbaset al-Megrahi for the bombing might have constituted a miscarriage of justice.

The late Libyan, an intelligence agent during the rule of deposed Libyan leader Muammar Gaddafi, was found guilty of bringing down the airliner in a special Scottish court in the Netherlands in 2001.

He was released by the United Kingdom's devolved Scottish Government on compassionate grounds eight years later after a diagnosis of terminal cancer, dying in Libya in 2012, protesting his innocence.

But the SCCRC declared that his family, who had sought a posthumous appeal against the verdict some three years ago, was now permitted to pursue an appeal against his near-two-decade old conviction.

"We were daring not to hope because every step along the way we have had to fight," lawyer Aamer Anwar, who filed the application with the SCCRC in 2017 on the instruction of Megrahi's family, told Al Jazeera. "It's one long chapter that is now shut - and it's the start of a new one."

A general view of floral tributes which were laid by the main memorial stone in memory of the victims of Pan Am flight 103 bombing, in the garden of remembrance at Dryfesdale Cemetery, near Lockerbie, Scotland [File: Scott Heppell/Associated Press]

Several relatives of victims have also celebrated the legal development.

Jim Swire collaborated with the al-Megrahi family on the SCCRC application. He lost his 23-year-old daughter Flora on the New York-bound flight that exploded over Scotland just 38 minutes after its takeoff from London.

Swire has long believed that al-Megrahi was innocent of the bombing - and is already looking ahead to the next phase of the judicial process which will see the case make its way to Scotland's High Court of Justiciary.

"I'm delighted that the case has been referred back to the Appeal Court - but I'm already concerned about how the case in the Appeal Court will be conducted," Swire, now in his 80s, tells Al Jazeera.

The Glasgow-based legal team highlighted six grounds why al-Megrahi's conviction constituted a grave miscarriage of justice - but the SCCRC upheld just two: "unreasonable verdict" and "non-disclosure" of evidence.

Al-Megrahi's conviction was largely secured on the basis that the clothes said to have been wrapped around the bomb were traceable to a shop in Malta owned by Tony Gauci, who testified to selling them to the Libyan.

But the SCCRC stated that a miscarriage of justice may have occurred as there was reasonable doubt about whether the individual purchasing clothes from Gauci was, in fact, al-Megrahi.

John Mosey, whose 19-year-old daughter Helga was killed in the bombing, also threw his support behind the application.

Speaking to Al Jazeera from his home in England, Mosey, a reverend, said the commission's decision, which prompted him to exclaim "Hallelujah", was the "end of a first step of a long battle".

Like Swire, he remains concerned that the grounds for appeal, as selected by the SCCRC, "are limited".

But the commission's decision will likely reopen painful wounds, especially in the United States where many victims' families and involved law enforcement officials continue to view al-Megrahi as guilty.

However, Richard Marquise, who led the FBI's US Lockerbie taskforce, told Al Jazeera that the "the circumstantial evidence" that put al-Megrahi behind bars in a Scottish jail "was overwhelming".

"I have seen the evidence; know, personally, some of the witnesses and; have read the entire transcript," said the retired special agent of the SCCRC's claim that "no reasonable trial court, relying on the evidence led at trial, could have held the case against Mr Megrahi was proved beyond reasonable doubt".

"Those who passed judgment from an ivory tower were never involved in the investigation, nor did they attend one day of trial."

In 2009, John Kerry, then-chairman of the American Foreign Relations Committee, outraged at al-Megrahi's release, declared that "the news today from Glasgow turned the word 'compassion' on its head".

Then-US president Obama described the move as "a mistake".

In this file photo, Libyan Abdel Baset al-Megrahi, who was found guilty of the 1988 Lockerbie bombing, left, and son of the Libyan leader Seif al-Islam Gaddafi, gestures on his arrival at an airport in Tripoli, Libya [The Associated Press]

Following the SCCRC decision, Anwar, the lawyer, told reporters that "a reversal of the verdict would have meant that the government of the United States and the United Kingdom stand exposed as having lived a monumental lie for 31 years, imprisoning a man they knew to be innocent".

Anwar contends that Libya was made a scapegoat for Lockerbie because it was a pariah state.

The SCCRC decision and forthcoming appeal, which he hopes will be heard next year after procedural hearings, could discomfort many in the international community, he said.

But while Swire has never wavered in his belief that al-Megrahi was innocent, he remains sympathetic to those relatives, not least in the US, who might lament last week's judgement.

"There are aspects of this case which profoundly need to be investigated because we have looked at it most closely in Britain and do not believe that this [verdict] represented either justice or truth," he told Al Jazeera.

"And we are hellbent on getting to justice and truth because to accept anything less seems like an insult to the memories of those in our families who died in the plane and on the ground."