One mysterious document, the work of a man now dead, holds the key to the credibility of Mr James Gogarty as a witness.
From the start of the tribunal, lawyers for Joseph Murphy Structural Engineering have indicated that they will fight tooth and nail to keep secret an affidavit filed against it by a former chief executive, Mr Liam Conroy.
Mr Conroy, who died last summer, brought an unfair dismissals case against JMSE in March 1989 in the Isle of Man, where Mr Joseph Murphy snr banks much of his wealth.
Mr Gogarty has told the tribunal that the affidavit accuses Mr Murphy of "everything under the sun". The document clearly refers to the company's management practices and tax affairs, and may back up some of Mr Gogarty's allegations about wrong-doings by his former employers.
More importantly, however, it probably contains crucial information which will enable the chairman, Mr Justice Flood, to rule on the essential clash of evidence in the tribunal.
On the last day of Mr Gogarty's direct evidence this rift between Mr Gogarty's version of events, and that of other JMSE executives and the developer Mr Michael Bailey, was never more apparent.
At issue is whether Mr Gogarty was acting under instructions, and specifically those of Mr Murphy, when he paid money to Mr Ray Burke in connection with the sale of lands in north Co Dublin, or whether he was engaged in a "frolic" of his own.
We weren't there, we weren't involved, sums up the JMSE response to the Burke allegation. Yet Mr Gogarty insisted again yesterday that Mr Joseph Murphy snr knew about the payment, and Mr Joseph Murphy jnr was present for it. "There was no frolic by me," he asserted.
Mr Justice Flood is thus left with a stark choice. Someone is lying. The tribunal lawyers may yet find evidence to back up Mr Gogarty's allegations, particularly by following the trail of the money which changed hands. If they don't produce supporting evidence, however, the credibility of the witness becomes of central importance. As of now, virtually all the accounts furnished by other parties are hostile to those given by Mr Gogarty.
Mr Conroy, though, stood in a position of conflict vis-a-vis JMSE in 1989, as Mr Gogarty does today. Though the two men were not friends, Mr Gogarty's lawyers believe that the dead man's affidavit may support their client's story.
According to Mr Gogarty, Mr Conroy helped Mr Murphy snr to recover millions of pounds he had lost in a failed business venture in the Isle of Man. However, Mr Conroy then assumed full responsibility for Mr Murphy's business and private affairs. By 1983, Mr Gogarty alleged last month, he was chief executive of both Mr Murphy's British and Irish trust companies.
Subsequently, however, Mr Murphy sought to reassert control, and Mr Gogarty participated in a move which ousted Mr Conroy and his management team some years later. Against this acrimonious background, Mr Conroy filed his affidavit, and Mr Gogarty was asked by JMSE to file an affidavit in response.
According to Mr Frank Callanan SC, for Mr Gogarty, the tribunal cannot possibly assess who was responsible for the sale of the lands without considering the Conroy affidavit.
Although Mr Gogarty was asked to identify the document from the witness box yesterday, the chairman ruled out opening it for now. However, as Mr Callanan said, "this is not a document which is going to go away".
The Conroy affidavit wasn't the only matter kept under wraps yesterday. The part of Mr Gogarty's evidence dealing with events surrounding an industrial dispute on the construction site of the ESB generating station at Moneypoint, Co Clare, was ruled out as irrelevant by the chairman.
Mr Gogarty's only new allegation yesterday came when he said that the former assistant Dublin city and county manager, Mr George Redmond, was owed "a few quid on top of that from previous services he provided" to Mr Conroy in JMSE.
Mr Redmond was again unrepresented at yesterday's hearing. He is understood to have made tentative approaches to a number of legal parties about possible representation during the cross-examination of Mr Gogarty. However, he still faces a £100,000 bill in legal fees arising from his representation at the tribunal up to this month and an unsuccessful High Court and Supreme Court application to have the allegations against him heard in private.
In his evidence yesterday Mr Gogarty firmly denied the allegations about him in an Irish Independent article of last week. He was not offered, nor did he seek, any money from Mr Michael Bailey, Mr Bailey's brother, Thomas, or their companies in order to secure the sale of the north Dublin lands. Apart from the £50,000 cheque he alleges Mr Bailey stuffed into his breast pocket, he received no other money from the Baileys in relation to the lands.
And so, quietly, Mr Gogarty's evidence came to an end in his fourth week in the witness box. The witness is to be "rested on grass", as the chairman put it, for a week, while the lawyers share and compare documents.
Next Wednesday, Mr Gogarty's cross-examination and, in all probability, the promised "big ambush" of him, will begin.