It is, of course, now all about oil. Only a simpleton could believe that Abdelbaset Ali al-Megrahi, convicted of responsibility for the Lockerbie bombing, was not recently returned to his home in Libya because it suited Britain. The political furore is very obviously contrived, since both the British and American governments know perfectly well how and for what reasons he came to be prosecuted. More important than the present passing storm is whether any aspect of the investigation that led to al-Megrahi’s original conviction was also about oil, or dictated by other factors that should have no place in a prosecution process.

The devastation caused by the explosion of Pan Am Flight 103 over Lockerbie, at the cost of 270 lives, deserved an investigation of utter integrity. Article 2 of the European Convention on Human Rights demands no less. Where there has been a death any inquiry must be independent, effective and subject to public scrutiny, to provide the basis for an attribution of responsibility and to initiate criminal proceedings where appropriate. But, in the absence of this, a number of the bereaved Lockerbie families have of necessity themselves become investigators, asking probing questions for two decades without receiving answers; they have learned sufficient forensic science to make sense of what was being presented at al-Megrahi’s trial and make up their own minds whether the prosecution of two Libyans at Camp Zeist near Utrecht was in fact a three-card trick put together for political ends.

Perhaps the result could have been different if there had been an entirely Scottish police investigation, with unrestricted access to all available information, without interference or manipulation from outside. Instead, from the beginning, the investigation and what were to become the most important aspects of the prosecution case against al-Megrahi were hijacked. Within hours, the countryside around Lockerbie was occupied: local people helping with the search under the supervision of Dumfries and Galloway police realised to their astonishment that the terrain was dotted with unidentified Americans not under the command of the local police.

Each aspect of every criminal investigation in Britain has to meet certain essential standards; where they are not met, these parts of the investigation should not in principle become the basis of a prosecution. There must be precise notes made of each physical exhibit found and by whom; its movements must be tracked; each time an exhibit is inspected, a record must be kept. The rationale is obvious: without a precise record, interference, contamination or simple mistakes could jeopardise a prosecutor’s reliance on evidence that should be tangible and therefore potentially more convincing. For that reason, a crime scene must be sealed off until searches are complete.

Those engineering the destruction of a transatlantic airliner in mid-flight might have believed that it would be likely to happen over the sea. Instead, Pan Am 103 was destroyed over the Scottish town of Lockerbie and its fall-out was scattered over an area too huge to cordon off. The first and most desperate searches were for the passengers: could any have survived? Volunteers included a police surgeon from Yorkshire who had driven to the site as soon as he heard the news; together with the local police, he and others searched non-stop for 24 hours. They found bodies, none showing any sign of life; the doctor labelled each of the bodies he found, more than 50 of them, noting the place of discovery. Once it was clear there were no survivors, a search for evidence of the cause of the explosion would begin.

Extraordinarily, however, distinct from the Dumfries and Galloway police, scores of men, some wearing no insignia, some the insignia of the FBI and Pan Am (it was noted at the time that many of these men were clearly not Pan Am staff), invaded the area. Lockerbie residents reported seeing unmarked helicopters hovering overhead, carrying men with rifles whose telescopic sights were pointing directly at them. And when, much later, items of baggage came to be married up with the passengers they had accompanied, there were disturbing signs of interference. The suitcase belonging to Major McKee (a CIA operative flying back to the US to report on his concern that the couriering of drugs was being officially condoned as a way to entrap users and dealers in the US) was found to have had a hole cut in its side after the explosion, while the clothes in the suitcase were shown on subsequent analysis to bear no trace of explosives. A second suitcase, opened by a Scottish farmer, contained packets of white powder which a local police officer told him was undoubtedly heroin; no heroin was ever recorded as having been discovered. All but two of the labels that Dr Fieldhouse attached to the bodies he found were removed and have never been found.

Although the crime was the most hideous Scotland had ever known, the integrity of the crime scene was violated; in part because outsiders were conducting a desperate search for wreckage that it was important for them to find and spirit away. As many police investigations over the years have demonstrated, such distracting irregularities can simply be red herrings, and these intrusions may have no bearing on the question of who blew up Pan Am 103. Was it individuals? Was it a country? And if so which one? From the very beginning, in fact, it seemed that the case could and would be easily solved. Considerable (and uncomplicated) evidence immediately to hand suggested who might be responsible; it was as if giant arrows were pointing towards the solution.

In the weeks before the bombing in December 1988 there had been a number of very specific warnings that a bomb would be placed on a Pan Am aircraft. Among them was a photograph of a bomb in a Toshiba cassette radio wired to a barometric timer switch; a number of such bombs had been found earlier in 1988 in the possession of members of a small group with a history of successfully carrying out bombings, primarily of American targets. One group member told police that five bombs had been made; at least one was missing at the time of the Lockerbie disaster and never recovered. The warnings were sufficiently exact that the staff of the American Embassy in Moscow, who usually travelled by Pan Am when they returned to the US for Christmas, used a different airline. Flora Swire, who was travelling to New York to spend Christmas with her boyfriend, found it surprisingly easy to buy a ticket.

All the Toshiba cassette bombs that had been seized were found, when tested, to run for 30 minutes after they were set. The advantage of barometric timers is that they aren’t activated until the plane is airborne – the bomb won’t go off on the ground if the plane is delayed. Some seven or eight minutes would elapse before the air pressure dropped enough as the plane gained height to activate a barometric timer set to go off 30 minutes later, i.e. 37 or 38 minutes after the flight took off. It was precisely 38 minutes after Pan Am Flight 103 took off from Heathrow on 21 December 1988 that it exploded over Lockerbie; when the remnants of the destroyed plane and its contents were put together piece by piece by the Dumfries and Galloway police, fragments of a Toshiba cassette radio were found.

Forensic scientists believed that the radio had been in a suitcase in which there were clothes whose label was traced to a shop in Malta. A search of the house of a man affiliated to the group that manufactured the Toshiba bombs produced clothes bought in Malta; it was established too that he had travelled to Malta before the bombing. And the owner of the Maltese shop from which the clothes were thought to have been purchased identified to his brother, without prompting, a newspaper photograph of that man as the person who had bought the clothes found in the suitcase with the bomb inside.

But the man who bought the clothes was not al-Megrahi, nor was he Libyan. The group making Toshiba radio cassette bombs had no connection at all with Libya. Neither the man nor the group was ever prosecuted for involvement in the Lockerbie bombing. The fact that the explosion took place exactly when one would have expected it to if a Toshiba cassette bomb had been used was ignored: the bomb had not, the prosecution contended at al-Megrahi’s trial, been triggered by a barometric switch in this way. The Lockerbie device, it claimed, was different from the devices made by the group. The difference was that it was a Toshiba cassette radio with one speaker rather than two. From a logically compelling case that seemed to point clearly in one direction the prosecution switched tack, but not at the beginning: not, in fact, until two years after the bombing, when the politics of the Middle East shifted and new allies had to be found quickly if the flow of cheap oil were to continue.

It is not difficult to achieve a conviction of the innocent. Over many decades several common factors have been identified, and the majority of them are present, centre stage, in this case: achieving the co-operation of witnesses by means of a combination of inducements and fear of the alternative (the tried and tested method of obtaining evidence for the prosecution on which many US cases rely); the provision of factual information by scientists where there is no proper basis for it (a recurrent theme in UK convictions as well as in the US); reliance on ‘identification’ evidence which is no such thing. Add to that the political will to achieve a prosecution, and the rest is easy. Fabrication demands outright dishonesty, but it isn’t always necessary, or necessary in every aspect of an investigation: the momentum of suspicion, and a blinkered determination to focus on a particular thesis and ignore evidence pointing to the contrary, is a certain route to achieving the desired end. Al-Megrahi is reported as saying that he has evidence, which will be revealed on his death, that will prove his innocence. But it is clear even from the evidence that can be looked at today that his conviction was extremely disturbing.

For the first two years there was no mention at all of Libya. The investigation originally seemed to have clear evidence of a motive (tit for tat retaliation); evidence of the existence of a bomb intended to destroy airliners in mid-flight contained in the same brand of cassette radio discovered on the plane; and evidence implicating a Palestinian splinter group, the Popular Front for the Liberation of Palestine – General Command, which was prepared at the time to hire itself out to regimes that were known to be state sponsors of terrorism; Syria was one (somewhat earlier, Libya had been another), so was Iran.

Behind every crime there is of course a motive. For the initial prime suspect, Iran, the motive was brutally clear. In July 1988 a US battleship, the Vincennes, shot down Iran Air Flight 655 in the Persian Gulf, with 290 passengers, many of them pilgrims en route to Mecca. There were no survivors. By chance a television crew was on the Vincennes when the attack took place and images of triumph at the carnage were immediately beamed around the world. When it became clear, as it did straight away, that the attack was an appalling error, the US compounded its mistake: President Reagan claimed self-defence and the ship’s commander and crew were awarded high military honours.

Two days after the downing of the Iranian airbus, Tehran Radio condemned the attack as an act of naked aggression and announced it would be avenged ‘in blood-splattered skies’. At the same time, US Air Force Command issued a warning to its civilian contractors: ‘We believe Iran will strike back in a tit for tat fashion – mass casualties.’ Warnings became more specific: ‘We believe Europe is the likely target for a retaliatory attack . . . due to the large concentration of Americans and the established terrorist infrastructures in place throughout Europe.’ Within days, US intelligence was convinced that Iran meant business; and the CIA in due course acknowledged that it had intelligence that Ahmad Jibril, the leader of the PFLP-GC, had met government officials in Iran and offered his services.

Such a partnership would indeed have been ominous, since the activities of the PFLP-GC had since 1970 included planting bombs on planes – bombs built into transistor radios and detonated by a barometric pressure switch. It was in this context that the flood of warnings immediately preceding the disaster had obvious significance for the subsequent investigation. One of them read: ‘team of Palestinians not associated with PLO intends to attack US targets in Europe. Time frame is present. Targets specified are Pan Am Airlines and US military bases.’ Five weeks before this warning, a PFLP-GC cell had been arrested in Germany. The PFLP-GC was precisely a ‘team of Palestinians not associated with the PLO’. Jibril’s right-hand man, Haffez Dalkamoni, was arrested in Frankfurt with a known bomb-maker, Marwen Khreesat, as they visited electrical shops in the city. In the boot of Dalkamoni’s car was a Toshiba cassette recorder with Semtex moulded inside it, a simple time delay switch and a barometric switch. Later US intelligence officials confirmed that members of the group had been monitoring Pan Am’s facilities at Frankfurt airport. Dalkamoni admitted he had supervised Khreesat when he built bombs into a Toshiba radio cassette player, two radio tuners and a TV monitor. He said that a second Toshiba containing similar pressure switches had been built. Although Dalkamoni was prosecuted in Germany, Khreesat was inexplicably released; it only later became clear that he had been acting throughout as an undercover agent for Jordanian intelligence, which is extraordinarily close to the CIA (the CIA played a central role in its creation). On Dalkamoni’s account, other bombs made by Khreesat were at large somewhere, including the one built into a second Toshiba player.

On 9 November 1988 Interpol circulated warnings about the PFLP-GC bombs. Heathrow Airport issued its own warning to security staff, stating that it was ‘imperative that when screening or searching radios, radio cassette players and other electrical equipment, staff are to be extra vigilant’. Over the next three weeks the airport received more information, including photographs of the Toshiba bomb from the German authorities. (A document giving information and advice was drawn up by the UK’s principal aviation security adviser on 19 December, but there were problems obtaining colour photographs and delays in the Christmas post and most airlines did not receive it until the new year, weeks after the disaster.)

In March 1989, less than three months after the downing of Flight 103, the then secretary of state for transport, Paul Channon, had lunch with some journalists. He talked, indiscreetly, of the brilliant detective work undertaken by the smallest police force in the country. Arrests, he told the journalists, were imminent. Although such conversations are customarily regarded as not for attribution, the next morning’s newspapers revealed that a cabinet minister had stated that those responsible for the Lockerbie bombing had been identified and would soon be arrested.

At precisely the same time, however, the US president, George Bush Senior, was reported by the Washington Post as having spoken to Margaret Thatcher about Lockerbie, advising her to keep Lockerbie ‘low-key’, to avoid prejudicing negotiations with Syrian and Iranian-backed groups holding Western hostages in Lebanon. There were no arrests; Channon left the cabinet; and political interest in the case and desire to identify who was responsible for the disaster disappeared. The victims’ families demanded evidence that a proper inquiry was being conducted and in September 1989 Channon’s successor, Cecil Parkinson, met the newly formed UK Families Flight 103. He promised them a full judicial inquiry. Thatcher countermanded this promise, and he returned to the relatives with an admission of total failure. ‘Low-key’ meant no judicial inquiry, no prosecution, and instead a Fatal Accident Inquiry with no powers to subpoena which declined to investigate how the bomb got on the plane for fear of interfering with police inquiries.

As political players grow old, they reminisce and sometimes they forget what they are meant to have said or not said. Five years later Parkinson took part in a television programme about another horrific disaster, the sinking of the Marchioness, in which he confirmed that it was Thatcher who had blocked a judicial inquiry. He remembered discussing with the Lockerbie relatives whether, ‘because the security services were involved’, a High Court judge could look into the security aspects and report privately to him: ‘Because when you get into the Lockerbie business – how did we find out certain information, how did we know this, how did we know that? – you would have had to recall not only our own intelligence sources but information we were receiving from overseas. Therefore that had to be a closed area.’ This suggested the real block.

Nevertheless, investigators had clearly remained confident that despite government diffidence a prosecution would soon be brought. Late in 1989 an imminent arrest once again seemed tantalisingly on the cards. The Sunday Times (known to enjoy detailed briefings from the police and security services) reported that the ‘net was closing’ on the Lockerbie suspects and stated categorically that the bombing had been carried out by the German PFLP-GC cell led by Dalkamoni under orders from Ahmad Jibril and with a bomb made by Khreesat. What was new was the suggestion that the bomb had first been put on a plane not in Frankfurt but in Malta. Clothes made in Malta, the report added, had been found in the suitcase in which police believed the bomb had been planted. A member of Dalkamoni’s cell, Abu Talb, who was then awaiting trial for separate offences in Sweden, had, it revealed, visited Malta. He was the man identified by the shop owner: the man who had clothes bought in Malta in his possession. The Sunday Times articles went on to predict that Abu Talb would be extradited at any moment to stand trial for the bombing.

The suggestion that the bomb was placed on a plane from Malta was made in an attempt to link the discovery of the Maltese clothes with the already existing evidence of the German group. As no passengers transferred from Air Malta to Pan Am 103A in Frankfurt, the feeder flight for Pan Am 103, it would have had to be an unaccompanied bag from Malta that carried the bomb. Two documents were said to have been discovered: a list of the stages followed by Frankfurt airport’s automated baggage system which related to Pan Am 103, and a handwritten worksheet from one of the several stations from which baggage came into the system. As this was official information, it must have been given lock, stock and barrel by investigators to the journalist in question.

A fundamental objection to the last part of the new thesis was blindingly clear: if the intended target was an American aircraft, why risk a premature explosion triggered by the barometric switch by putting the suitcase on an Air Malta flight? The scientific underpinning necessary to support a counter-proposition was established during 1989 and 1990 and rested on two ‘discoveries’: a fragment of an entirely different type of timer in the remnant of a shirt collar and the matching of that fragment with the manufacturer’s prototype. This timer, it was argued, could, once set, keep a barometric switch from detonating for days. It was in the development of this proposition that every safeguard fundamental to a criminal investigation came to be jettisoned.

That Iran and the PFLP-GC were responsible had fitted comfortably with UK and US foreign policy in the Middle East. Both countries had severed relations with Syria on the grounds of its persistent support for international terrorism; both had supported Iraq in the Iran/Iraq war, which ended in the summer of 1988. The obvious truth as it appeared at the time was that the Jibril group, sponsored in this instance by Iran, was a logical as well as politically acceptable fit.

Then, in August 1990, Saddam Hussein invaded Kuwait, thereby putting at risk almost 10 per cent of US oil supplies, and the stability of the Saudi and Gulf sheikhdoms on which the West depended to preserve the status quo in the region. A sudden shift of alliances was necessary: if Iraq had to be confronted, then Iran had to be treated differently and the Syrian regime needed to be brought on board. At the beginning of 1991 Syrians joined Western troops in the attack on Saddam Hussein’s invading army.

The centre of the Lockerbie investigation had by this time ceased to be Scotland: the CIA was in charge. Vincent Cannistraro had made his mark under Ronald Reagan, with a clandestine programme to destabilise the Libyan regime. He boasted that he ‘developed the policy towards Libya’ which culminated in the bombing of Gaddafi’s house in Tripoli in 1986 on the basis of intercept evidence later acknowledged to be false. Now brought out of retirement, Cannistraro shifted the investigation’s approach. The suspect country was no longer Iran but Libya, and in November 1991, the UK and the US made a joint announcement that two Libyan Airlines officials, Abdelbaset Ali al-Megrahi and Al Amin Khalifa Fhimah, had planted the bomb in Malta on behalf of Libyan intelligence. Douglas Hurd, the foreign secretary, announced to the House of Commons that Libyans alone were suspected and that other countries were not implicated.

Years of protracted negotiations were to take place before the Libyan government agreed to release the two men to stand trial in a ‘neutral country’. It was not until May 2000 that the two Libyan Airlines officials who had run the airline’s office in Malta finally went on trial – in a purpose-built court outside Utrecht created from a mothballed air-force base – under Scots law, albeit before three judges rather than a jury. What did Gaddafi expect when he agreed to the extradition of the two men? That they would in due course be exonerated because they were innocent but that he would meanwhile reap the diplomatic benefit by having delivered them? The idea of their individual responsibility was anyway peculiar: as agents of a state where not a mouse squeaks without the say-so of Gaddafi, al-Megrahi and Fhimah were either ordered to do what it was said they did, in which case dealing with Gaddafi as a statesman then and now has been beyond hypocrisy – or the thesis was wrong.

The key features needed to prosecute al-Megrahi successfully were the scientific identification of the circuit-board fragment, which would in turn establish its origin, and the identification of the purchaser of the clothes in Malta. The timers, the indictment stated, were made by a firm in Switzerland; their circuit board matched the fragment retrieved from Lockerbie, and they sold the timers exclusively to Libya. Everything, essentially, hinged on those links.

Who found the fragment? And who understood its relevance? Thomas Hayes of the Royal Armament Research and Development Establishment (RARDE) claimed the find (with his colleague Alan Feraday) and Thomas Thurman of the FBI claimed the analytical victory. All were swiftly hailed (or hailed themselves) as heroes. Thurman appeared on television on 15 November 1991, the day after indictments were issued against the two Libyans, boasting that he had identified the piece of circuit board as part of a timing device that might have been sold to Libyan Airlines staff. ‘I made the identification and I knew at that point what it meant. And because, if you will, I am an investigator as well as a forensic examiner, I knew where that would go. At that point we had no conclusive proof of the type of timing mechanism that was used in the bombing of 103. When that identification was made of the timer I knew that we had it.’ This was the claim – the hard evidence – that linked Libyans to the crime. If the claim was false the bereaved Lockerbie families have been deceived for 20 years.

On 13 September 1995 the FBI’s forensic department was the subject of a programme broadcast in the US by ABC. At its centre was a memorandum from the former head of explosive science at the FBI, Dr Frederic Whitehurst. It was a devastating indictment of a former colleague. The colleague was Thomas Thurman and the accusations related to his investigation of a terrorist attack in which a judge was killed by pipe bombs. Two years later, as a result of a review by the US inspector general, Michael Bromwich, into a large number of criminal investigations, Thomas Thurman was barred from FBI labs and from being called as an expert witness. Bromwich had discovered that he had no formal scientific qualifications and that, according to a former colleague, he had been ‘circumventing procedures and protocols, testifying to areas of expertise that he had no qualifications in . . . therefore fabricating evidence’.

Thurman had made the Libyan connection, and its plausibility relied on the accuracy of his statement that the fragment of circuit board proved that it would have been possible for the unaccompanied bag to fly from Malta without the seemingly inevitable mid-air explosion. And thus it was that a witness from Switzerland, Edwin Bollier, the manufacturer of the MEBO circuit board, was called on to provide evidence that such boards had been sold exclusively to Libya. Bollier was described by al-Megrahi’s barrister in his closing speech as an ‘illegitimate arms dealer with morals to match’. The evidence he was clearly intended to provide had begun to unravel even before the trial began. Sales elsewhere in the world were discovered, Thurman did not appear at the trial, and the judges commented that Bollier’s evidence was ‘inconsistent’ and ‘self-contradictory’. Other witnesses, they found, had ‘openly lied to the court’. Despite all this al-Megrahi was convicted.

Bollier had been one of the most potentially dubious of many dubious witnesses for the prosecution. But Dr Köchler, the UN’s observer throughout the trial, recorded that Bollier had been ‘brusquely interrupted’ by the presiding judge when he attempted to raise the issue of the possible manipulation of the timer fragments. Could the MEBO board, or a part of one, have been planted in such a way that it could be conveniently ‘discovered’? After the trial, new evidence that would have been at the centre of al-Megrahi’s now abandoned appeal made this suggestion more credible: a Swiss electronics engineer called Ulrich Lumpert, formerly employed by Bollier’s firm, stated in an affidavit to Köchler that in 1989 he stole a ‘non-operational’ timing board from MEBO and handed it to ‘a person officially investigating in the Lockerbie case’. Bollier himself told Köchler that he was offered $4 million if he would connect the timer to Libya.

There were throughout two aspects of the investigation over which the Scottish authorities exerted little authority: in the US, the activities of the CIA and in particular of Thomas Thurman and the forensic branch of the FBI; in England, the forensic investigations of RARDE, carried out by Hayes and Feraday. Without Hayes’s findings, the Lockerbie prosecution would have been impossible. His evidence was that on 12 May 1989 he discovered and tweezed out from a remnant of cloth an electronic fragment, part of a circuit board. The remnant of cloth, part of a shirt collar, was then traced to a Maltese shop. A number of aspects of the original circuit board find were puzzling. The remnant was originally found in January 1989 by a DC Gilchrist and a DC McColm in the outer reaches of the area over which the bomb-blast debris was spread. It was labelled ‘cloth (charred)’ by him, but then overwritten as ‘debris’ even though the fragment of circuit board had not yet been ‘found’ by Hayes. The fragment found by Hayes, and identified as a MEBO circuit board by Thurman, meant that the thesis of an Air Malta involvement could survive.

Even if one knew nothing of the devastating findings of the public inquiry in the early 1990s into the false science that convicted the Maguire Seven or of the succession of thunderous judgments in the Court of Appeal in case after case in which RARDE scientists had provided the basis for wrongful convictions, Hayes’s key evidence in this case on the key fragment should be viewed as disgraceful. There is a basic necessity for evidential preservation in any criminal case: every inspection must be logged, chronology recorded, detail noted. But at every point in relation to this vital fragment that information was either missing or had been altered, although Hayes had made meticulous notes in respect of every single one of the hundreds of other exhibits he inspected in the Lockerbie investigation.

No forensic scientist knows when he conducts his examinations whether or when there will be a prosecution that will depend on them; this makes it all the more important that his notes are exact. Hayes confirmed that it was his practice to draw pieces of circuit board where he found them – for instance in the vicinity of blast-damaged material – but he made no such drawings of this item, nor had he given it an exhibit reference number as he had every other exhibit being designated at the time, nor did he carry out a standard test for traces of explosive. Almost a month after his inspection of the timer fragment, Hayes was identifying and drawing exhibits which were given reference numbers smaller than the number of the vital exhibit. He recorded his finding on page 51 of his notes, but the pages originally numbered 51-55 had been renumbered 52-56 at some point. Hayes stated that he had ‘no idea’ when the change in pagination was carried out. The inference put to Hayes was that the original page 51 and the following pages had been renumbered, an original page removed and space made to insert what was now page 51 of his notes.

Curiously, a memorandum from Hayes’s colleague Feraday, written on 15 September 1989, to a detective inspector working on the case, referred to a fragment of green circuit board: ‘Willy, enclosed are some Polaroid photographs of the green circuit board. Sorry about the quality, it is the best I can do in such a short time.’ No one was able to explain why there should have been any shortage of time to make available in September 1989 photographs of an item that had been found on 12 May. Feraday’s note continued: ‘I feel that this fragment could be potentially most important so any light your lads or lasses can shed upon the problem of identifying it will be most welcome.’ Again no one was able to explain what light the lads and lasses could shed on something it was most curious they had not seen before now, given that Hayes had recovered it in May. Clearly it could not have been seen by the police before the cloth was passed to Hayes at RARDE and the fragment extracted by him. If Hayes had photographed the exhibit, as was his normal practice, then Feraday would not have needed to rely on Polaroids of dubious quality. The issue of his notes’ pagination was described by Hayes as ‘an unfathomable mystery’. In view of the importance of exhibit PT/35(b), how could the court have been satisfied by this evidence? The new evidence of the former MEBO employee who stole a circuit board would of course have been ripe for analysis by the Court of Appeal, which has now been discharged from considering new evidence in al-Megrahi’s lately abandoned appeal.

A secondary important proposition for the Crown to consider was that the suitcase was on the second layer of a luggage container on the aircraft – which meant that it must have come from Frankfurt. Examining the largest surviving fragment of the outside case of the Toshiba device on 25 January 1989, Hayes had considered its state consistent with its having been at the base of the container. This would have contradicted the Crown’s position that the device was in a suitcase that had arrived last, as unaccompanied baggage from Malta via Frankfurt, and so was nearer the top. By the time he gave evidence at the trial, Hayes had revised his assessment of its position.

(Since the trial, evidence new to the defence but known from the start to the police has surfaced of a break-in at Heathrow in the hours before the disaster. The Fatal Accident Inquiry, which didn’t have this knowledge, had made a finding in 1991 that Pan Am 103 was ‘under constant guard at Heathrow’. Iran Air’s hangar at Heathrow was next to Pan Am’s.)

This isn’t the first time we have heard of Hayes and Feraday. Among the many wrongful convictions in the 1970s for which RARDE scientists were responsible, Hayes played his part in the most notorious of all, endorsing the finding of an explosive trace that was never there, and speculating that a piece of chalk mentioned to the police by Vincent Maguire, aged 16, and a candle by Patrick Maguire, aged 13, ‘fitted the description better’ of a stick of gelignite wrapped in white paper. Both were convicted and imprisoned on this evidence, together with their parents and their uncle Giuseppe Conlon, who was to die in prison. All were later found to be innocent.

Although Feraday was often addressed by the prosecution as ‘Dr’ or ‘Professor’ when he gave evidence, he had no relevant academic qualifications, only a higher national certificate in physics and electronics some 30 years old. Dr Michael Scott, whose evidence has been preferred in appeals to that of Feraday, commented that ‘the British government employed hundreds of people who were extraordinarily well qualified in the areas of radio communication and electronics. Alan Feraday is not qualified yet they use him. I have to ask the question why.’ Feraday, like his US counterpart Thurman, has now been banned from future appearances as an expert witness, but he had already provided the key evidence in a roll-call of convictions of the innocent. A note of a pre-trial conference with counsel prosecuting Danny McNamee (who was wrongly convicted of involvement in a bombing in Hyde Park) provides a typical instance: ‘F [Feraday] prepared to say it [a circuit board] purely for bombing purposes, no innocent purpose.’ The implication here was that anyone who had involvement with this circuit board would have knowingly been involved in bomb construction. That, in common with many other assertions made by Feraday, was entirely false, but it resulted in McNamee’s imprisonment for 11 years.

To discover that al-Megrahi’s conviction was in large part based on the evidence of scientists whose value as professional witnesses had been permanently and publicly demolished ten years before his trial is astounding. The discovery nearly two decades ago of a large number of wrongful convictions enabled by scientific evidence rightly led to demands that the community of forensic scientists change its ways. Similarly, a series of catastrophic misidentifications required the introduction of sound new practices for evidence based on that most fragile of human attributes, visual memory. Witnesses must not be prompted; a witness’s memory, as far as possible, must be as safely protected from contamination as a crime scene. The first description is vital. If a witness makes a positive identification of one individual, no subsequent identification of a second is permissible. Equivocation and uncertainty are not enough. Even if the science that convicted al-Megrahi had not offended against every minimum standard, then the second pillar of the prosecution case, his identification by Tony Gauci, the Maltese shopkeeper, would remain spectacular in its noncompliance with any safeguard. He described al-Megrahi as ‘6’0’’’ (he was 5’8’’), ‘50 years old’ (he was 37), and ‘hefty’; said that he ‘had been to the shop before and after’, ‘had been there only once’; that he ‘saw him in a bar months later’; that he ‘will sign statement even though I don’t speak English’; that al-Megrahi ‘was similar but not identical’, ‘perhaps like him but not fully like him’, and, fatally for any identification of al-Megrahi in the first place, that he was ‘like the man in the Sunday Times’ (in other words, like Abu Talb, whose picture Gauci had initially identified). But Gauci’s evidence was needed and, reports suggest, handsomely rewarded. He apparently now lives in Australia, supported by millions of US dollars.

That a court of three experienced judges convicted on such evidence and that an appeal court upheld the conviction is profoundly shocking. Köchler, the UN observer, reported finding the guilty verdict ‘incomprehensible’ in view of the court’s admission that Gauci’s identification was ‘not absolute’. We had come to believe that such an outcome, resting on invalid identification, was no longer possible. ‘The guilty verdict’, Köchler wrote, was ‘arbitrary, even irrational’ with an ‘air of international power politics’ present ‘in the whole verdict’, which was ‘based on a series of highly problematic inferences’. He remarked on the withholding of ‘substantial information’ (‘more or less openly exercised influence on the part of actors outside the judicial framework’) and on the very visible interference with the work of the Scottish prosecutors by US lawyers present in the well of the court. But most seriously, he set out his ‘suspicion that political considerations may have been overriding a strictly judicial evaluation of the case’. All of this harks back to the bad old days when a blind eye was turned to the way convictions were obtained.

Al-Megrahi’s trial constituted a unique legal construct, engineered to achieve a political rapprochement, but its content was so manipulated that in reality there was only ever an illusion of a trial. Dr Köchler recorded at its conclusion that it was ‘not fair’ and that it was not ‘conducted in an objective manner’, so that there were ‘many more questions and doubts at the end than the beginning’. Since then, these doubts have not disappeared: on the contrary, the questions are graver, the doubts have grown and so has the strength of the evidence on which they are based. Köchler’s observations continue to have compelling relevance; he found the respect of the court, the defence lawyers included, for the ‘shrouds of secrecy’ and ‘national security considerations’ to be ‘totally incomprehensible to any rational observer’. ‘Proper judicial procedure,’ he continued, ‘is simply impossible if political interests and intelligence services – from whichever side – succeed in interfering in the actual conduct of a court.’

The term miscarriage of justice carries with it the inference of accident, but also of death. There is a pressing need to investigate in detail how it has come about that there has been a form of death in this case – the death of justice – and who should be found responsible.