When Pan AM Flight 103 exploded over the skies of Lockerbie on December 21, 1988, killing all 259 passengers and a further 11 people on the ground, Scotland's police forces were suddenly thrust into the centre of the largest terrorist investigation in Britain's history.
s far as the investigators were concerned, the hunt for those responsible finished 13 years later with the successful conviction of Abdelbaset Ali al-Megrahi, a former Libyan intelligence officer whom a jury at a special court in the Netherlands decided was the man who placed the bomb on the plane.
But while Britain and America have firmly stood by Megrahi's conviction, many people -- including a number of British families who lost loved ones in the tragedy and the UN-appointed observer at the trial -- were convinced the real culprits remained at large while an innocent man was jailed.
It took more than three years for western intelligence agencies to start blaming Libya for Lockerbie and in that time a number of disparate terrorist groups had claimed responsibility, including Islamic Jihad, the little-known Guardians of the Islamic Revolution and even, allegedly, the Ulster Defence League.
But it was the Popular Front for the Liberation of Palestine-General Command (PFLP-GC), a small Palestinian terror network based in Lebanon and Syria with strong links to Iran, that investigators were most keen to concentrate on in the bombing's aftermath.
Two years before Lockerbie, PFLP-GC's Syrian leader Ahmed Jibril had called a press conference warning that there would be "no safety for any traveller on an Israeli or US airliner".
Intelligence agencies took this to mean that Tehran had given Mr Jibril the go-ahead to carry out a revenge attack for the shooting down of an Iranian Airlines passenger jet by the US warship Vincennes. Iran Air Flight 655 had been carrying 290 pilgrims to Mecca for the hajj.
Two years later the very threat that Mr Jibril had promised to carry out had happened. The PFLP-GC hastily called a press conference in Beirut denying any involvement but many believed the organisation carried out the attack on behalf of Iran in revenge.
Those who do not believe the official verdict say Libya was placed in the frame three years later because the US could not afford to alienate Iran and Syria during the build-up to the first Gulf War.
By November 1991, two Libyan intelligence officers, Megrahi and Al Amin Khalifa Fhimah, were indicted for the bombing. The announcement sparked nearly a decade of negotiations between Britain and Libya's leader Muammar Gaddafi, who finally agreed to have his subjects tried in Dutch court under Scottish law in return for the UN lifting crippling sanctions on his nation. But as the trial progressed many of the families began having doubts.
The case against Megrahi and Mr Fhimah was largely based on the testimony of a Maltese shopkeeper, Tony Gauci, who said he had sold clothes to Megrahi, fragments of which were found around the Samsonite suitcase which allegedly carried the bomb. Megrahi was found guilty and sentenced to 27 years in a Scottish prison. Mr Fhimah was acquitted.
In September 2001 Ray Manley, a former security guard at Heathrow, said in a sworn affidavit that he had told anti-terror police that one of Pan Am's luggage rooms had been broken into on the night of the bombing. Mr Manley was surprised his evidence had not been presented in court.
From his jail cell in Greenock prison, Megrahi continued to protest his innocence and launched appeal attempts. At first they were rejected out of hand but a four-year investigation by the Scottish Criminal Case Review Commission concluded last year that Mr Gauci's evidence against Megrahi was questionable enough to warrant an appeal which would have gone ahead had Megrahi not dropped it this week. The SCCRC's 400-page dossier will now likely never see the light of day.
Those families who hoped Megrahi's appeal would have shed new light on who was behind the murder of their loved ones have called for a full public inquiry. (© Independent News Service)