For the past two years or more Padraig Collery has been under the type of pressure most people would find difficult to imagine. Not only has the computer systems expert and former Guinness & Mahon banker been discovered running an unauthorised bank designed to facilitate tax evasion, he is also is facing a massive personal tax bill on undeclared earnings of more than £0.5 million.

In addition, the legal and other professional bills he has run up since the discovery of the Ansbacher deposits by the McCracken tribunal in 1997 must be enormous. And all the time the possibility of criminal charges has been hovering.

Collery has spent hours in the witness box of the McCracken and Moriarty tribunals and has also been interviewed, most likely at length, by an authorised officer, Gerard Ryan, appointed by Mary Harney two years ago to investigate the deposits. And more recently he has been questioned by the three High Court inspectors appointed last September as a result of Ryan's work.

And for all this time Collery has known that Denis Foley had an account in the Ansbacher deposits but did not disclose the fact. He was asked by the Moriarty tribunal, under oath, who owned a coded account, which he knew belonged to Foley, but he went ahead and said it belonged to the Cayman Islands banker, the late John Furze.

While repeatedly telling the tribunal he was giving it his full co-operation, Collery travelled secretly to the Cayman Islands in July 1998 to help to put order on the accounts of a Cayman company which holds some of the Ansbacher deposits. The trip was paid for by Barry Benjamin, a US national who now controls the affairs of the company, Hamilton Ross Co Ltd. Collery spent half his time working on the accounts, and the other half lying on a 7 1/2-mile beach.

He must have needed the break.

A few weeks after his return Collery met Foley at Dublin Airport for a brief discussion in relation to Foley's affairs. Foley's account was among those he had worked on during his trip to Cayman.

During the year that followed Collery continued to keep Foley's involvement secret. Both men say there was no contact between them about it. Last September Ms Harney successfully applied to the High Court for the appointment of inspectors to Ansbacher Cayman, and the temperature rose considerably.

Massive publicity was given to the fact, revealed during the application, that Ryan's report listed 120 people, 100 of whom were Irish residents. The total involved could be hundreds of millions of pounds, the court was told.

With names being published in the newspapers amid political uproar, Collery lost his nerve. He thought his phone was being tapped and began to worry that someone would break into his house to steal the highly sensitive documents he kept there. He had a copy of Ryan's report, but he also had something else: documents brought back from his July trip to the Caymans and not handed over to any of the authorities he was supposedly co-operating with.

He decided it was not safe to keep them at home: he said he feared a break-in rather than a raid. The documents he took from his house were not those, such as the report, which might reveal the names of his former clients, but documents which might in the future provide him with "protection".

Collery went to the home of his former secretary in Guinness & Mahon, Margaret Keogh, and asked her to hide a sealed package of documents. But Keogh, after consulting her solicitor, gave the documents to the Moriarty tribunal. Foley's name and account details were in them.

The financial and political consequences for the Kerry TD will be huge.

However, what has also emerged is that Collery seems to believe some people could lose the money they invested in the Ansbacher deposits. Hamilton Ross Co Ltd was run by Furze and looked after funds for a number of people including Foley, Charles Haughey, Des Traynor, Collery himself and perhaps 20 others.

In March 1997, realising that the McCracken tribunal was going to discover the deposits, Furze withdrew the money from Irish Intercontinental Bank in Dublin, and had it transferred to the Cayman Islands. Up to then Collery had been looking after the accounts held here. Back in the Cayman Islands Furze, in bad health and under great pressure as a result of the tribunal, failed to create proper books. In July 1997 he had a heart attack and died.

Collery travelled to the Cayman Islands in 1998 to help Barry Benjamin, Furze's executor, bring the accounts up to date. He brought back handwritten copies of the calculations, for "protection" in case of future difficulties. He feared that depositors might not, further down the line, be able to get their money and would take action against him. He wanted to be able to prove that everything was in order up to the time, March 1997, he transferred responsibility to the Cayman Islands.

He said an interview with Benjamin, carried in The Irish Times on Monday, increased that concern. Benjamin is refusing to give Irish residents details of their affairs until they can prove to him they are the individuals whose names he has on a list he has been provided with. Collery has managed to close his account and repatriate his funds.

The reason Collery gave to the Moriarty tribunal for not disclosing Denis Foley's involvement was that he was unsure whether the account belonged to Foley, or Foley and one of his daughters. He said the concern arose after his August 1998 meeting with Foley when, he said, Foley said he had given an instruction that year to Des Traynor to put the account into his and his daughter's names. Foley denies saying this to Collery.

Even if Foley did say this to him, Collery could not give a clear reason why this made him tell the tribunal the account belonged to Furze. It was pointed out to him that he gave Foley £50,000 from the account in 1995, met Foley in relation to the account in August 1998, and sent Foley account statements on the account last May. He never made any attempt to contact Foley's daughter.

JOHN COUGHLAN SC, for the tribunal, repeatedly told Collery this week that he found his explanation "wholly incredible". The chairman of the tribunal, Mr Justice Moriarty, said the reason given did not appear plausible. When Collery was retiring from the witness box on Thursday, after giving 14 hours of evidence over five days, Moriarty said he wanted to ask him more questions in relation to his evidence and would recall him at a later date.

Of all the people involved in the Ansbacher deposits, Foley, as a sitting TD, is arguably the most important to the tribunal's terms of reference. Collery, as a result of his actions, risks losing some or all of his legal costs, and could face criminal charges.

Why did he do it? Foley was a sitting TD but otherwise was not a particularly powerful figure or important customer. The money he invested in the Ansbacher deposits came from dance-hall receipts in Tralee and Ballybunion during the 1960s and 1970s.

His long-time friend and partner in these affairs, John Byrne, was named at an early stage in the whole Ansbacher deposits scandal. Byrne is a hugely successful property developer and friend of Haughey whose main companies are owned by a Cayman holding company linked to Ansbacher Cayman. In the years 1991 to 1997 Byrne's companies borrowed £17.5 million sterling from Irish Intercontinental Bank, in loans secretly backed by funds in the Ansbacher deposits.

So why the Kerry TD and former rate collector? On a number of occasions during the week, Collery denied he had been placed under any pressure or offered any inducement for hiding Foley.