Detailed records of the Fianna Fail leader's allowance account which had been kept in the former Taoiseach's office have apparently disappeared, the tribunal heard.
The account administrator, Ms Eileen Foy, said she had no recollection of what happened to the ledgers in which she recorded details of each cheque drawn on the account.
Nor had she knowledge of the whereabouts of the cheque stubs on which the payee and purpose of every cheque were noted.
She understood that some documents had been moved when Mr Charles Haughey left office in 1992, but she did not know whether specific items were taken by him.
She noted, however, that when she asked the former Taoiseach last year whether he had any records relating to the account, "I did not really get an answer."
Mr John Coughlan SC, counsel for the tribunal, confirmed that "neither the files, the cheque stubs, nor the ledgers are now available."
Ms Foy resigned as private secretary to Mr Haughey in February 1992, when he was succeeded as leader of Fianna Fail and Taoiseach by Mr Albert Reynolds. As it was a time of great upheaval, she said, her memory of events was unclear.
She did not know whether specific items were included in boxes taken by Mr Haughey when his office was cleared, or what happened to the boxes.
But she said she had the impression that some of the material may have gone to Fianna Fail headquarters at Mount Street in Dublin.
She did not make any inquiries from anyone within the Fianna Fail party except Mr Haughey, whom she visited about a year ago.
"I said that I had been asked about all of this and I had no records and had he, and I did not really get an answer."
She added that she personally did not keep any material relevant to the account.
Later Ms Foy gave evidence as to how donations received for the benefit of the late Mr Brian Lenihan were treated.
Mr Lenihan became seriously ill in the late 1980s. His condition deteriorated and ultimately he required extensive medical treatment including a liver transplant. At the time, this treatment was not available in Ireland and he received it instead in a clinic in Rochester, Minnesota, in the United States.
Ms Foy said the treatment was extremely expensive and "contrary to what was understood at the time" Mr Lenihan's medical insurance did not meet all the costs.
She said that during 1989 "a considerable number of donations were received." These were usually given directly to Mr Haughey who would pass them on to her for lodgement in the Fianna Fail leader's allowance account at AIB Baggot Street. It was the former Taoiseach who initiated this practice.
She said all such donations would have been made in the strictest confidence. She would never have discussed the existence of the donations or the identity of the donors with anyone else and consequently she could not now remember their identities.
Invoices for Mr Lenihan's medical treatment were sent to the Taoiseach's office and were passed on to Ms Foy. She could not recall how these were paid but said it was probably by bank drafts in US dollars.
Looking at the major lodgements in the party leader's allowance account between June and July 1989, she said, they could be related to donations to Mr Lenihan. On the other hand, they could relate to political donations to Fianna Fail. The run-up to the general election on June 15th of that year was "hectic," she remarked.
In relation to this sensitive issue, Mr Coughlan said the late Mr Lenihan's family had been informed and was "happy to deal with this matter in the tribunal."