It was a winter's night in 1988. Tony Gauci was getting ready to close up Mary's House, his rather drab shop on Tower Road in Sliema, Malta. At about 6.30pm, a stranger entered the shop and bought a list of items so long and unlikely for conditions on the Mediterranean island that it became etched in Mr Gauci's memory.

From his recollection, when interviewed by the police nine months later, it was a rainy night in early December.

His brother Paul, with whom he ran the store, was absent as he was watching football. The Christmas lights were not yet up.

The customer's purchases included a baby sleepsuit, a tweed jacket and an umbrella. The charred remnants of these items were later found to have been inside a brown hardshell Samsonite suitcase that contained the bomb which blew up over Lockerbie on December 21, 1988, killing 270 people.

When PanAm flight 103 exploded, the impact was such that the British Geological Survey registered a seismic event measuring 1.6 on the Richter scale. Debris was strewn along an 81-mile corridor of Scottish countryside. Working out who was responsible was not going to be easy.

But it had to be worked out. This was the biggest case ever dealt with by Scottish police forces and the worst terrorist atrocity on mainland Britain.

Officers believed if they could trace the clothes from the suitcase they would find their man and, once they linked the items to Mary's House, they began to feel optimistic. Eighteen years on, that optimism seems like a false dawn.

Tony Gauci is, according to those who know him, a simple and honest Maltese shopkeeper whose only passion is for his racing pigeons. Unwittingly, he became caught up in one of the most controversial trials of the century.

From September 1989, Mr Gauci repeatedly changed his statements to the police. Perhaps, he said, it was November when the man came into the shop. Perhaps this was not the same man. The list went on.

He maintained that it was raining and the purchaser put up the umbrella as he left the shop to hail a taxi. From the point of view of the prosecution and, ultimately, the court at Camp Zeist, it was vital to prove that the purchase took place on December 7 - a date when Abdelbaset Ali Mohmed al Megrahi was known to be in Malta. On that day, Megrahi was even staying at the Holiday Inn, just across the crossroads from Mary's House.

The trial court referred to Mr Gauci as an "important witness" and said his identification of the Libyan as the clothes purchaser "should be treated as a highly important element in this case".

Despite the inconsistencies in his 19 different statements to the police, even the appeal court described Mr Gauci as reliable. However, during the three-year investigation by the Scottish Criminal Cases Review Commission, new evidence came to light which indicated that four days before an ID parade at which he picked out Megrahi, Mr Gauci saw a photograph of the Libyan in a magazine article linking him to the bombing.

"In the commission's view, evidence of Mr Gauci's exposure to this photograph in such close proximity to the parade undermines the reliability of his identification of the applicant at that time and at the trial itself," according to the report.

In addition, meteorological records show it was not raining in Sliema on that December night, and even the night in question was undermined by new evidence, which suggested the town's Christmas lights had gone up by December 6.

All the evidence, in fact, suggests that any purchase was made on November 23 at a time when Abu Talb, originally the key suspect in the case, was in Malta.

In May 1989, the Scottish police found clothing bought in Malta in the German flat of Talb, a member of the Popular Front for the Liberation of Palestine General Command (PFLP-GC) who is currently serving a life sentence in Sweden for bombing a synagogue in Denmark in 1985.

Talb was known to have visited Malta some weeks before the bombing. A calendar found in his flat had the date December 21 circled: the night of Lockerbie.

The PFLP-GC was headed by Ahmed Jibril, a former Syrian army captain, based in Damascus and backed by Iran. The group had a cell active in Frankfurt and, on October 26, 1988, German police, in an operation codenamed Autumn Leaves, arrested 17 terrorist suspects who had cased Frankfurt Airport and browsed PanAm flight timetables.

However, before any reinvestigation of Lockerbie turns to Talb as a possible suspect, the Scottish courts have to deal with Megrahi's appeal and whether his defence team is entitled to access to all of the documents seen by the Crown.

Sources claim that the CIA's offer of money and relocation to Tony Gauci may have been turned down on the grounds that he could not and would not leave his pigeons. He would travel to Scotland and Camp Zeist to give evidence but go no further.

Damningly, the revelation that such riches were offered to him and his brother - a fact not disclosed to the defence - may prove to be the final nail in the coffin of the Crown's case against Megrahi. Six points of issue

THE review commission found six grounds on which to refer the case back to the courts and, with yesterday's revelation about the CIA's $2m offer to the Gaucis, they are known in full for the first time. 1 No reasonable basis for trial court's judgment that purchase of clothes from Mary's House took place on December 7, 1988. This was only date on which it could be proven Megrahi was in Malta and had time to buy clothes. 2 It was not proven with sufficiency that Megrahi was purchaser. The commission found further disparities between Tony Gauci's various statements and inconsistencies between his memories and factual information. 3 New evidence not heard at trial suggested Christmas lights near his shop were illuminated on December 6. Mr Gauci said lights were not on when clothes were bought, indicating they were purchased prior to that date. 4 New information which undermines Mr Gauci's identification of Megrahi shows that, four days before the ID parade at which he picked out Megrahi, he had been shown a photograph of the Libyan which linked him to the bombing. 5 Non-disclosure of top secret classified report about MST13 timer which was allegedly used to detonate Lockerbie bomb. 6 Documents which suggest Tony Gauci and his brother Paul were offered financial remuneration of up to $2m by US intelligence agencies. Scottish police were aware of such discussions and yet this information was not disclosed to the defence.