The best was kept until last when evidence right at the end of yesterday's hearing suggested a previously unknown discussion in January 1998 between the banks and the Revenue on the non-resident account issue.
When a senior Revenue official popped up at the end of the hearing to say he had note of a meeting with AIB and Bank of Ireland in January 1998 - before media reports first surfaced on the issue of non-resident accounts - the committee obviously felt it had no option but to look into the entire issue again. The precise significance of this, however, has still to be established.
As a result, witnesses from the Revenue and from AIB and its auditor PricewaterhouseCoopers (PwC) have been called back today and the expected start of cross-examination by the AIB and Revenue of each others evidence looks set to be postponed.
After sifting through millions of documents, the committee had recently uncovered a note of a meeting between AIB and its auditors (PwC) last year which created the impression that the bank had been in contact with Mr Dermot Quigley, the Revenue chairman, and his predecessor, Mr Cathal Mac Domhnaill, regarding the "amnesty" AIB insists it was granted almost 10 years ago.
The note, prepared by a PwC partner, Ms Mary Walsh, recorded that AIB held a discussion with Mr Mac Domhnaill to clarify the status of the tax write-off it believed it had shortly after details of a potential £100 million tax liability was reported in the Sunday Independent last year.
The memo also referred to a subsequent phone call from Mr Quigley after he took over as Revenue chairman, which seemed to contradict its previous understanding.
Ms Walsh's version of what happened at that meeting was discredited by the bank and she readily accepted yesterday that her note was "incorrect" in a number of respects.
Asked how the names of the two Revenue chairmen came to appear in her report, she said she was aware that Mr Quigley had recently been appointed to that position. Later on, Mr Mac Domhnaill and Mr Quigley strongly rebutted the suggestion that they had ever discussed, let alone approved, a deal with AIB in 1991 to write off its DIRT liabilities.
Later, however, the current Revenue chairman, Mr Quigley, disclosed a meeting and a subsequent telephone call with AIB's senior tax adviser and former Revenue official, Dr Donal de Buitleir, last October, around the time the two organisations were due to appear before the Public Accounts Committee.
Mr Quigley said he met Dr de Buitleir the day before the hearings but they did not discuss any aspect of the disputed settlement. Two days later he made a "courtesy call" to Dr de Buitleir, he said.
Interestingly, though, this meeting and telephone conversation between Mr Quigley and AIB's senior tax official occurred shortly before the bank's subsequent meeting with Ms Walsh. And while she has accepted her note was "incorrect" there was nonetheless a meeting with the Revenue chairman and a subsequent phone call around that time.
Mr Mitchell suggested to Mr Quigley that these conversations with AIB could be viewed as being a "little bit sensitive" given that they took place just when the PAC was investigating the issue. The Revenue chairman replied that the meeting didn't affect his evidence.
However, the real drama came subsequently as Ms Walsh was recalled late in the day. Questioned by Mr Jim Mitchell she again referred to a meeting between AIB and the then Revenue chairman, Mr Cathal Mac Domhnaill, although she insisted this was not a reversal of her earlier evidence.
In the resulting confusion, the chief inspector of taxes, Mr Christopher Clayton, intervened to say that Mr Mac Domhnaill had been present in January 1998 at a meeting between AIB and Bank of Ireland to do with the issue of non-resident account forms. This was before the first media disclosures in April of last year.
It is clearly an interesting issue for the committee to investigate.