20 May 2012 Last updated at 15:46 ET

Lockerbie and Megrahi: Timeline

Abdelbaset Ali al-Megrahi, the only man convicted of the 1988 bombing of American Pan Am flight 103 over Lockerbie, killing 270 people, was released from a Scottish prison on compassionate grounds in 2009.
It was thought he had only months to live as he had terminal prostate cancer, but he lived on to see the fall of Colonel Gaddafi in Libya.
Here is a timeline of how events unfolded.

21 December 1988

270 die in Lockerbie bombing

Pan Am flight 103 from London to New York explodes 31,000 feet above southern Scotland. All 243 passengers and 16 crew on board the Boeing 747 are killed. 189 are Americans, many returning home for Christmas. In the Dumfriesshire market town of Lockerbie, 11 residents die in a fireball when wreckage hits the ground.
13 November 1991

Libyans indicted

The US Attorney General and Scotland's Lord Advocate jointly indict two Libyans for the bombing. Abdelbaset ali Mohammed al-Megrahi, the head of airline security for Libyan Arab Airlines, and Al Amin Khalifa Fahima, LAA's manager in Malta, are accused of 270 counts of murder, conspiracy to murder and breaching the UK's Aviation Security Act 1982.
15 April 1992

Sanctions imposed

United Nations sanctions are imposed on Libya over Colonel Muammar Gaddafi's refusal to hand over the two suspects, alleged to be Libyan secret service agents, for trial. UN Security Council resolution 748 bans arms sales to Libya. Sanctions will later be tightened, freezing Libyan bank accounts and targeting supplies for the oil and aviation industries.
5 April 1999

Suspects surrender

After lengthy negotiations, Megrahi and Fahima are flown from Tripoli to Camp Zeist, a former military base in the Netherlands where the case against them will be heard by three Scottish judges sitting without a jury. The two men gesture with victory signs as they leave the Libyan capital. The UN suspends sanctions against Libya.
3 May 2000

Trial begins

The two Libyans go on trial at the Scottish Court in the Netherlands. Both men plead not guilty to the charges against them. Their lawyers say they will produce evidence incriminating others for the bombing including a Palestinian terrorist cell in Germany. An air traffic controller becomes the first of 230 witnesses to give evidence.
31 January 2001

Megrahi found guilty

Megrahi is convicted of 270 counts of murder in a judgment which says the airliner bombing plot was "of Libyan origin". One victim's relative calls it a verdict of "state-sponsored terrorism". The judges recommend a sentence of at least 20 years imprisonment "in view of the horrendous nature of this crime." Fahima is acquitted.
23 January 2002

Appeal launched

Five Scottish judges, also sitting at Camp Zeist, begin hearing an appeal against Megrahi's conviction. The Libyan's lawyers claim fresh evidence has emerged which casts doubt on his guilt. The Crown insists the new evidence does not affect the safety of the verdict. In a Scottish legal first, the appeal is broadcast live on television.
14 March 2002

Appeal rejected

Megrahi loses his appeal and begins a life sentence in Glasgow's Barlinnie prison. Libya condemns the decision as a "political verdict" handed down under pressure from Washington and London.
16 August 2003

Libya "accepts responsibility"

In a letter to the UN Security Council, Libya accepts formal responsibility for the Lockerbie bombing, saying it "has facilitated the bringing to justice of the two suspects" and "accepts responsibility for the actions of its officials".
22 August 2003

Relatives receive compensation

Libya pays $2.7bn compensation to relatives of those killed in the bombing, with each family set to receive $9.6m (£6m). The deal paves the way for the lifting of United Nations sanctions on the country.
12 September 2003

Sanctions are lifted

UN sanctions against Libya, suspended since 1999, are formally lifted. There are 13 votes for the draft resolution, none against, and two abstentions - France and the US, which was set to maintain its own separate sanctions on Libya.
25 Nov 2003

New jail term for Megrahi

The minimum term Megrahi must serve in jail before being allowed to apply for parole is set at 27 years, backdated to 1999, after European law requires Scotland's courts to set more precise sentences.
29 May 2007

Deal in the desert

The British prime minister, Tony Blair, visits Libya, holding talks in a tent with Colonel Gaddafi and announcing that the oil giant BP will return to the country after an absence of more than 30 years. It emerges that a memorandum of understanding is signed covering prisoner exchanges.
28 June 2007

Second appeal

Megrahi is granted leave to make a second appeal against his conviction. The Scottish Criminal Cases Review Commission says the four main areas for referring the case back to court include the "reasonableness" of the court's verdict; additional evidence; new evidence and "other" evidence.
28 August 2008

Gaddafi's son recants

Colonel Gaddafi's son and presumed heir, Saif al-Islam al-Gaddafi, tells the BBC that Libya only accepted responsibility for the Lockerbie bombing and paid compensation so sanctions would be lifted. "It doesn't mean that we did it," he insists.
21 October 2008

Megrahi has cancer

Megrahi's solicitor reveals that his client is suffering from advanced prostate cancer but insists that the "fight to overturn his wrongful conviction" will continue.
29 April 2009

Prisoner treaty signed

A prisoner transfer agreement between the UK and Libya is ratified, allowing Megrahi to apply to serve the remainder of his sentence in Libya.
5 May 2009

Tripoli requests Megrahi's return

The Libyan authorities request Megrahi's transfer to Libya. A prisoner transfer would not be possible while criminal proceedings continue, which means he cannot return to Libya unless he drops his appeal or is granted compassionate release.
25 July 2009

Megrahi asks for mercy

Megrahi applies to the Scottish government for compassionate release, as he continues to receive treatment for "advanced stage" prostate cancer.
18 August 2009

Appeal abandoned

Megrahi abandons his second appeal, apparently to remove a potential obstacle to his transfer to a jail in Libya. Megrahi's legal team say his illness has reached the "terminal stage" and his condition has worsened considerably. Appeal Court judges in Edinburgh accept the application.
20 August 2009

Megrahi freed

The Scottish Justice Secretary Kenny MacAskill rejects the request for Megrahi to be transferred to a Libyan jail, opting instead to release him on compassionate grounds on the basis that he has around three months to live. Megrahi is flown back to Tripoli and a hero's welcome.
23 August 2011

Fall of Tripoli

Libyan rebel forces overrun Colonel Gaddafi's compound as they take control of the Libyan capital. There is no sign of Col Gaddafi himself. There are calls for Megrahi to be sent back to prison in the UK or to be taken to the United States to serve out his sentence.
6 September 2011

Megrahi 'very ill'

Family members invite the BBC to film Megrahi, apparently gravely ill, at his family home in Tripoli to end speculation about the state of his health. Fresh allegations emerge about the circumstances surrounding his release as a former Libyan foreign minister claims it was linked to a contract for oil company BP.
20 October 2011

Gaddafi killed

Colonel Gaddafi is shot dead after being found by rebels in his hometown of Sirte. Relatives of those who died in the Lockerbie disaster say his death should not be an obstacle to continuing investigations into the atrocity.
22 December 2011

'Last' interview

Megrahi gives what he describes as his "last interview" and again denies any involvement in the bombing. He says: "I am an innocent man. I am about to die and I ask now to be left in peace with my family."
23 February 2012

Prosecution request

A formal request is sent to the new Libyan government seeking access to the country for police and prosecutors involved in the Lockerbie bombing case. The Libyan National Transitional Council has previously confirmed to the UK government that it will assist the ongoing criminal investigation.
2 May 2012

Libya visit

Scotland's top prosecutor joins the director of the FBI on a mission to Libya to discuss the investigation into the bombing. The lord advocate tells the Libyan prime minister he hopes that there will be a positive response to his recent request for co-operation.
11 May 2012

Voters register

Libya is struggling to prepare for landmark elections due in the middle of June. Voters will elect a new National Public Conference, which will choose a government and draft a new constitution.
20 May 2012

Megrahi death announced

Abdelbaset al-Megrahi dies at his home in the Libyan capital Tripoli. His family says his funeral will take place at the city's main cemetery. Scottish First Minister Alex Salmond pays tribute to the dead and says the investigation into the bombing continues.