The High Court has ordered an expert on rare books to stop representing himself as the owner of letters written to an Irish priest by the late Jackie Kennedy.
The court granted temporary injunctions against Eoin Felix O'Neill, with an address in Cahir, Co Tipperary.
The court was told he may have taken photos of some of the letters without permission of their owners or seller and provided those photos to a US newspaper.
Mr Justice Peter Kelly was told that Mr O'Neill appeared to have been "miffed" at not being mentioned in connection with the discovery, when articles were published concerning the letters, which extend from 1950-1964, in the Irish Times earlier this week.
The archive of the correspondence with Fr Joseph Leonard, a Vincentian priest who lived in All Hallows College in Drumcondra, Dublin will be sold at an auction here on 10 June.
Mr O'Neill, who was present at All Hallows College in Dublin when the existence of the letters was first disclosed to Sheppard's auctioneers, would be entitled to commission in relation to the sale of the letters, the judge noted.
When Mr O'Neill realised they were likely to attract substantial amounts, it seemed he became disenchanted with the terms of that commission, the judge added.
The court was told Mr O'Neill walked out of a meeting with Philip Sheppard and Michael Sheppard earlier this week, after making "strange comments".
Mr O'Neill's alleged assertion he was going to "get the letters sold" appeared to be a "ridiculous" claim when the letters were not his to sell, the judge added.
He granted additional orders restraining Mr O'Neill publishing any of the letters or any extracts or holding himself out as having the authority to negotiate their sale or publication.
The orders were sought by Maurice Collins SC, for Sheppard's, on the basis of concerns Mr O'Neill may have photographed some of the letters and may have been behind the publication of some of the letters by the Boston Globe this week.
The interim orders, were granted by Mr Justice Kelly who directed no details of the making of them could be published before 8pm, after concerns were expressed Mr O'Neill might be alerted by media reports to the orders being made before they could be served.
MJ Fine Art Ltd, trading as Sheppard's Irish Auction House, of Durrow, Co Laois, also got another order restraining Mr O'Neill passing on any confidential information or trade secrets of the firm.
The orders were granted as part of intended proceedings where the firm is also seeking damages against Mr O'Neill.
The court was told Mr O'Neill had been a client of the firm for some years and last December agreed to act as a consultant to it concerning rare books for which he was paid expenses and commission representing 3% of the "hammer price".
There was no written contract and the firm said it had offered to pay Mr O'Neill an additional sum relating to the Kennedy letters.
In evidence, Philip Sheppard said he felt it was put under pressure to do so by Mr O'Neill and that meant Mr O'Neill was getting a percentage of the sale of material not within his particular expertise.
He was concerned Mr O'Neill's actions could adversely impact on the value of the letters which could attract bids from between €800,000 to €3m.
The letters were "effectively the autobiography" of Jackie Kennedy, a very private person, and there was "enormous interest" in them worldwide, he said.
His firm became aware of the letters after representatives from All Hallows attended a valuation evening hosted by the firm at Dublin's St Stephen's Green Club seeking a valuation of a 15th century manuscript and other items.
As a result of that evening, representatives of the firm and Mr O'Neill later visited the college library when they were shown the letters.
The college also held a painting by Sir John Lavery and portraits by the Irish artist Leo Whelan.
His firm agreed to sell the letters, extending to some 130 pages, for the college at auction and it was always understood the college's identity as owner and seller would be kept confidential, as was the firm's practise, Mr Sheppard said.
He believed Mr O'Neill was aware of the confidentiality obligations.
It was arranged for extracts from the letters to be published in the Irish Times as a "teaser" to generate interest.
When the first Irish Times articles and a supplement was published last Tuesday, Mr O'Neill appeared miffed and unhappy he was not credited with their find in some way, Mr Sheppard said.
The following day, 14 May, the Irish Times reported All Hallows owned the letters and suggested the reasons for the sale was because the college was experiencing financial difficulties.
Mr Sheppard said Mr O'Neill had disclosed that information which was "a total breach of confidentiality" and a betrayal of the firm and All Hallows.
An article about the letters was also published in the Boston Globe which stated the letters had been bought by Mr O'Neill, a rare books dealer, and the Boston Globe also published what appeared to be photographed reproductions of them were published without authority of his firm or All Hallows, extending to some 13 pages, Mr Sheppard said.
These were not the letters provided to the Irish Times and it was "utterly untrue" they were purchased by Mr O'Neill.
As a result of those developments, he and his cousin Michael met with Mr O'Neill hoping to resolve the matter but Mr O'Neill was "verbally aggressive" and said he was going to get the letters and get them sold, he added.