The former Fianna Fáil TD, Mr Liam Lawlor, has been directly implicated for the first time in attempts to rezone the controversial land which is currently under investigation by the Flood tribunal.
Two witnesses are to tell the tribunal they attended a meeting with Mr Lawlor and the owner of the land, Mr James Kennedy, in Leinster House in 1991, it emerged yesterday.
Mr Lawlor was present "in a consultative capacity" at the meeting, at which discussions took place about how an application could be made to have lands now owned by Jackson Way rezoned.
The revelation by consulting engineers Mr Brian O'Flanagan and Mr Frank Finnegan confounds Mr Lawlor's denial of any involvement with the land and his repeated denial of a business relationship with Mr Kennedy.
It also appears to confirm Mr Frank Dunlop's characterisation of the former TD as the "Mr Big" behind rezoning on Dublin county council.
However, Mr Dunlop's claim that he was approached by two county councillors who were concerned about Mr Lawlor's possible involvement in Jackson Way has been contradicted by the politicians concerned.
Mr Lawlor is staying with his son in the US for Thanksgiving and could not be contacted last night.
Fine Gael's Ms Olivia Mitchell TD and former Senator Therese Ridge both say they have no recollection of approaching Mr Dunlop on this matter, as Mr Dunlop has alleged.
Yesterday's evidence was dominated by denials of impropriety by the councillors who received money from Mr Dunlop.
The former Fine Gael TD, Mr Liam Cosgrave, categorically denied, in a statement to the tribunal, receiving payments in return for votes on rezoning motions at meetings of Dublin County Council.
He admitted receiving what he called "several election donations" to offset election expenses. "They were bona-fide electoral donations," he said.
Mr Cosgrave said he took grave exception to "the innuendo and malicious rumours" being put about that he had voted for motions for ulterior motives and not in the best interests of his area.
However, it also emerged yesterday that Mr Cosgrave was summonsed to appear before the Flood tribunal last year after he failed to comply with repeated requests for a detailed statement.
In a letter ordering the former Fine Gael senator to give evidence in Dublin Castle in March 2001, Mr Justice Flood expressed his disappointment that a member of the Oireachtas had failed to submit a statement to the tribunal voluntarily.
Mr Cosgrave filed the detailed statement a short time after and the summons lapsed.
The tribunal heard that Mr Dunlop received a £30,000 "incentive fee" for lobbying county councillors to rezone property adjoining the Jackson Way lands.
Mr Brian O'Halloran, an architect who owned the 22 acres of land at Carrickmines along with businessmen Mr Gerard Kilcoyne and Prof Austin Darragh, said he also paid Mr Dunlop a total of £6,500 in ordinary professional fees during the 1990s.
In his statement, Mr O'Halloran listed payments totalling £4,000 to Fianna Fáil and £500 to Fine Gael, as well as £250 to Mrs Mary McAleese during the 1997 presidential election campaign.
He told the tribunal in his statement that these were normal political contributions.