Taoiseach Bertie Ahern first asked AIB in December 2004 about specific transactions which have since become the focus of the tribunal's inquiries, the tribunal was told.
Jim McNamara, a bank official with AIB O'Connell Street, Dublin, said the bank was first contacted by Mr Ahern in late 2004. The first request to the bank from the tribunal for information came later.
Mr Ahern's solicitor was contacted by the tribunal on October 15th, 2004, and told that an allegation had been made by developer Tom Gilmartin concerning alleged payments to Mr Ahern, and advising that the tribunal would seek banking and other documentation from Mr Ahern.
In November the tribunal informed Mr Ahern's solicitor that it would be seeking information from January 1988 to December 1995, initially in relation to lodgments over £30,000.
A bank document bearing Mr McNamara's handwriting shows him making inquiries into Mr Ahern's affairs on December 16th, 2004. The document contains contact details for two of Mr Ahern's secretaries.
Mr McNamara said he did not know why Mr Ahern's request to him for information was focused on certain transactions, when the tribunal request to Mr Ahern had been non-specific as to transaction.
One transaction being inquired into in December 2004 was for £24,838.49. This was the lodgment of money which Mr Ahern has since said he received in a "dig-out" from friends in Ireland, and a gift of approximately stg£8,000 which he was given in Manchester.
"I do not know why Mr Ahern asked for that single particular transaction at that particular time," Mr McNamara said.
The same document also listed six other specific transactions involving Mr Ahern's accounts. One was the lodgment of another "dig-out" or goodwill loan received by Mr Ahern. A second was the lodgment Mr Ahern said came from £50,000 in cash savings. A third was another lodgment from the cash savings. The withdrawals include two, totalling £50,000 in December 1995 which have also since become the focus of the tribunal's inquiries.
"I don't have the specific answer as to why he picked on those transactions," Mr McNamara said.
He said the only information he had was that there was going to be a tribunal inquiry.
He agreed that all of the amounts being inquired into at that stage, at the request of Mr Ahern, were of less than £30,000 and so were not covered by the tribunal's order of that time.
In January 2005 Mr McNamara furnished the results of his inquiries to one of Mr Ahern's secretaries, including copy documentation. He said he "may have" communicated directly with Mr Ahern.
He said he did not recall being told by Mr Ahern that the £24,838.49 lodgment included sterling notes. He was not sure why he sought the retrieval of information from the foreign-currency-held account for the date in October 1994 when the £24,838.49 deposit was made. The account showed the total amount of sterling purchased by AIB O'Connell Street on the day in question.
Tribunal counsel Des O'Neill SC said the only explanation for this was that Mr McNamara was checking to see if the lodgment by Mr Ahern was "shown in the records of the bank as being a foreign exchange transaction". Mr McNamara agreed and said this came as a surprise to him now, though he could not explain this.
By May 2005, the tribunal was looking for background documentation linked to specific transactions, including the October 1994 lodgment. Everything being supplied to the tribunal was also being supplied to Mr Ahern.
Mr O'Neill said that by November 2005 the tribunal had narrowed its focus to eight specific transactions linked to Mr Ahern at AIB O'Connell Street. The branch's inquiries into these matters led to a letter being written in which it was "confirmed" that the £24,838.49 lodgment was a cash deposit. Mr McNamara said this response was premised on the lodgment being an Irish pound transaction.
Mr McNamara said that at the time he confirmed that the deposit was an Irish pound lodgment, he did not recall his earlier inquiry concerning the foreign currency held account.