The National Asset Management Agency is seeking to question the son of developer Seán Dunne under oath in its attempts to find out more about the Co Carlow man's finances.
The State property agency has issued John Dunne with legal papers, either a subpoena or notice of deposition, seeking to ask him questions as part of its trawl for information about his father's business.
Mr Dunne jnr, whose father went bankrupt with debts of $942 million (€690 million), is in his late 20s and living in New York where he is building a luxury commercial development at a cost of $21.5 million (€15 million).
Mr Dunne revealed that Nama is seeking information from his son in a filing dated July 28th, 2014, in the United States bankruptcy court district of Connecticut, Bridgeport division. He states that Nama began this process involving his son on June 25th, 2014.
Mr Dunne snr accuses Nama of “abusing the discovery process” and of going on a “vast fishing expedition” by seeking information from his son as well as 13 other parties including banks, lawyers and various advisers.
Mr Dunne snr makes the accusation as part of an attempt by the developer to question Brendan McDonagh, the chief executive of Nama.
An American judge has rejected this request by the bankrupt property developer but Mr Dunne maintains he should be allowed quiz Mr McDonagh in order to be given a “fair opportunity to prepare for trial”.
Mr Dunne argues it is "not credible" that Mr Donagh does not have "unique knowledge" about him and his interactions with Nama.
John Dunne like his father is now based in the US along with his stepmother, Gayle Killiea Dunne. He is leading the development of 74 Grand Street in Manhattan using his company TJD21. John Dunne is listed on New York planning files as the main shareholder of that company.
In May, John Dunne and Gayle Killiea Dunne received planning permission to build a $21.5 million apartment and retail building in the fashionable Soho neighbourhood of New York.
The planners approved a six-metre yard ensuring the profit the Dunne’s are projected to make on the development is $3 million.
The reason Nama, one of Mr Dunne's largest creditors, is challenging his discharge from bankruptcy is that it alleges Ms Killilea is developing property with money fraudulently transferred from her husband. This is a claim the Dunnes deny.
The Soho property was bought last year for $4.95 million in cash and the company has estimated that four apartments in the building could each sell for between $3.3 million and $7.7 million.
Earlier this year it also emerged that John Dunne has written to his father's Irish bankruptcy trustee demanding the return of boxing gloves signed by Muhammad Ali and a Manchester United jersey signed by Ronaldo as he claims he owns them and they were wrongly seized from a house in the K Club, Co Kildare.
