Lockerbie bomber Abdelbaset Ali al-Megrahi has died in Tripoli, his brother said today.
Megrahi was sentenced to life in prison for the 1988 bombing of a US airliner over the Scottish town which claimed 270 lives.
He was released from jail on August 20 2009 on compassionate grounds after being diagnosed with terminal prostate cancer and sent home to Tripoli with an estimated three months to live.
The decision by Scottish Justice Secretary Kenny MacAskill to free the only man convicted of bombing of Pan Am flight 103 provoked an international storm.
His death at his Tripoli home at the age of 59 was announced today by his son, Khaled.
The Foreign Office said it was investigating reports.
The bombing of the American plane, travelling from London to New York four days before Christmas, killed all 259 people on board.
Eleven residents of the Dumfries and Galloway town also died after the plane crashed down on their homes in Britain's biggest terrorist atrocity.
After protracted international pressure, Megrahi was put on trial under Scots law at Camp Zeist in the Netherlands.
He was found guilty in 2001 of mass murder and was ordered to serve a minimum of 27 years behind bars.
Despite claims that he could not have worked alone, and the lingering suspicion by some that he was innocent, Megrahi was the only man ever convicted over the terrorist attack.
He was freed from prison having served nearly eight years of his sentence after he dropped his second appeal against conviction at the Court of Criminal Appeal in Edinburgh.
Mr MacAskill's decision to allow him to return home to die in Libya sparked international condemnation from some relatives of victims and politicians, who demanded he be returned to jail.
US families were among the most vocal critics of the decision, along with US president Barack Obama. US secretary of state Hillary Clinton branded the move “absolutely wrong”.
American fury at the decision was compounded by the hero's welcome Megrahi received in Tripoli upon his return.
Prime Minister David Cameron has also come under pressure from some US senators for an independent inquiry into the decision to free the bomber.
But the move attracted support from some victims' relatives in Britain, and high profile figures such as Nelson Mandela and Archbishop Desmond Tutu.
David Ben-Ayreah, a spokesman for the victims of Lockerbie families, said: “I was told seven days ago by very good sources in Tripoli that he was slipping in and out of quite deep comas, that the secondary tumours had affected his abdomen and lower chest, and that he had had three blood transfusions.
“His death is to be deeply regretted.
“As someone who attended the trial I have never taken the view that Megrahi was guilty.
“Megrahi is the 271st victim of Lockerbie.”
In August 2009, Mr MacAskill's said the decision to allow Megrahi to return home to die was based on a medical report provided to him by Dr Andrew Fraser, the director of health and social care at the Scottish Prison Service.
His report described the three-month prognosis as "reasonable" but stated that no-one "would be willing to say" if Megrahi would live longer.
The bomber's death comes two years and nine months after his release from Greenock prison.
Scottish ministers have always insisted that their decision was made in good faith, on compassionate grounds alone and followed the due process of Scots law.
But those who opposed the decision insisted Megrahi should not have been freed.
With each anniversary connected to Megrahi's controversial release, calls were repeated for an apology from the Scottish Government and for more evidence to back up the decision.
Megrahi had rarely been seen since his return to Tripoli, but he was spotted on Libyan television at what appeared to be a pro-government rally in July.
UK Foreign Secretary William Hague said the public appearance confirmed that a "great mistake" was made in releasing him from jail.
Prior to Megrahi's death, reports suggested his prostate cancer had spread to his neck.
Others said he had been kept alive with cancer drugs unavailable in the UK.
Consultant urologist professor Roger Kirby, founder and director of The Prostate Centre in London, said he believed that abiraterone was likely to have been responsible for Megrahi's prolonged life well beyond the three-month point.
Last month Megrahi was reported to have been admitted to hospital for a blood transfusion.
He protested his innocence to the end.
During his time in jail in the UK, Megrahi fought against his conviction.
He lost an appeal in 2002 but was given the chance to launch a second legal battle in 2007 when the Scottish Criminal Cases Review Commission (SCCRC) referred his case back to senior judges.
Following a £1.1 million, three-year investigation into the case, the commission said there were grounds where it believed a miscarriage of justice may have occurred.
The appeal in full got under way in April 2009, almost two years on from the SCCRC's referral, but was dropped by the Libyan two days before he was released.
The SCCRC's report, which raised questions about identification evidence that led to Megrahi's conviction, has not been made public, but the Scottish Government has pledged to bring about a change in the law to allow the paperwork to be published.
The Justice for Megrahi (JFM) campaign group called for an independent inquiry to look again at the conviction.
Jim Swire, whose daughter Flora was killed in the bombing, said Megrahi's death was a "very sad event".
Dr Swire, a member of JFM, believes there is evidence yet to be released that will prove Megrahi's innocence.
"It's a very sad event," he told Sky News.
"I met him last time face-to-face in Tripoli in December last year, when he was very sick and in a lot of pain.
"But he still wanted to talk to me about how information which he and his defence team have accumulated could be passed to me after his death.
"And I think that's a fairly amazing thing for a man who knows he's dying to do.
Dr Swire added: "Right up to the end he was determined - for his family's sake, he knew it was too late for him, but for his family's sake - how the verdict against him should be overturned.
"And also he wanted that for the sake of those relatives who had come to the conclusion after studying the evidence that he wasn't guilty, and I think that's going to happen."
Despite sparking international controversy, and a vote symbolically rejecting the decision in the Scottish Parliament, Megrahi's release from prison appeared to have had no effect on the SNP's fortunes.
The party, with Mr MacAskill, was returned to power at Holyrood in a landslide victory in May last year.
Martin Cadman, from Norfolk, whose son Bill died in the flight at the age of 32, said: "The only thing I am interested in is getting to the truth. The Americans know far more than they have said."
JFM, which represents victims' families who are sceptical over Megrahi's responsibility for the bombing, has called for the appeal against his conviction to be reopened.
Megrahi abandoned his appeal shortly before his release on compassionate grounds, despite the fact that he was under no legal compulsion to do so.
Mr MacAskill strongly denied claims in a book co-authored by Megrahi that he urged the Libyan to drop the appeal to smooth the way for his compassionate release.
In the book, Megrahi claimed he was passed a message by Mr MacAskill that "it would be easier to grant compassionate release if I dropped my appeal".
Mr Swire recently told MSPs that the victims' families could push for the appeal to be reopened after Megrahi's death.
Speaking in February, Dr Swire said: "The professional advice that I have received is that it would be perfectly possible for other individuals affected by the case to approach the SCCRC (Scottish Criminal Cases Review Commission) to request that a further appeal be granted.
"In that event, I understand that number one in the pecking order, as it were, would be Megrahi's family, to whom I have spoken.
"In the event that they did not wish to pursue an appeal, it would perhaps fall to other people affected by the case such as me, unfortunately, and those who support what we have been trying to do, to do so."
Mr Cadman said today that he would welcome the reopening of the appeal.
He said: "I would be very happy for that to happen. A lot of evidence pointed to the fact that the Americans knew that the attack was coming. They needed someone to blame and the finger fell on Megrahi, but I think he is innocent. I don't believe it was the work of one man alone."
Scottish Labour leader Johann Lamont said: "Megrahi was convicted by a Scots court, under Scots law, of the greatest act of mass murder in Scottish history.
"Three years ago the Scottish government chose to release him on the pretext he had just three months to live. That was an insult to the victims.
"At this moment let me, on behalf of the people of Scotland, apologise to the families of all the victims of the Lockerbie bombing, for his early release."
Scottish Liberal Democrats leader Willie Rennie said: "Although this is an end to a chapter of one of the worst terrorist events in Scotland there should be no celebration that Abdelbaset al-Megrahi has died.
"Instead it should act as a spur to establish the facts including whether crucial forensic evidence was withheld from the trial."
JFM secretary Robert Forrester said Megrahi's eldest daughter Gadha, who studied law in Scotland, has often signalled her intention to push for the appeal to be reopened after her father's death.
In the event that she declines, Mr Forrester said Dr Swire and other sceptical families would be likely to do so.
However, he accused the SNP administration at Holyrood of actively obstructing efforts to shed light on the Lockerbie affair.
He said: “The Crown and successive governments have, for years, acted to obstruct any attempts to investigate how the conviction of Mr al-Megrahi came about.
“Some in the legal and political establishments may well be breathing a sigh of relief now that Mr al-Megrahi has died. This would be a mistake.
“Many unfortunates who fell foul of outrageous miscarriages of justice in the past have had their names cleared posthumously.”
He added: “Historically, all the major parties, both in Holyrood and Westminster, must shoulder equal responsibility.
“However, since first coming to power in 2007, the SNP government has actively taken measures which hinder any progress towards lifting the fog that lies over events, much to the dismay of its own party supporters and activists who take an interest in the case.
“In 2009, a statutory instrument which was supposed to remove the legislative prohibition on publication of the SCCRC's statement of reasons for the second appeal was so drafted as to render publication effectively impossible.
“In 2010, the government also fired new legislation through parliament that makes any prospect of opening another appeal in the interests of justice a forlorn hope.”
Scotland Office Minister David Mundell, whose Dumfriesshire, Clydesdale & Tweeddale constituency includes Lockerbie, said: “Obviously, one commiserates with family members at the time of a death, whatever the circumstances.
“Mr Megrahi's passing is the end of a chapter, but not the end of the story that has unfolded since that terrible night in 1988.
“It will not bring closure to all those bereaved or otherwise caught up in that tragic event and who want answers.
“So, that quest goes on and I still hope that the new regime in Libya can play a part in delivering those answers.
“I recently visited Syracuse University in New York State.
“Thirty five Syracuse students died in the Lockerbie bombing and it is they and all the other 270 victims that should be and remain in our thoughts.”
Former Liberal Democrat leader and Scottish QC Sir Menzies Campbell said: "This brings to a satisfactory end a controversial series of events which began with the terrible and tragic loss of life over Lockerbie.
"The decision to release Mr Megrahi was ill-judged and undermined confidence in the Scottish legal system.
"Answers to many of the outstanding questions have died with Mr Megrahi."