The leader of the Bon Secours order in Ireland has been accused in court of "lying through her teeth".
The claim was made as the High Court was urged to help a man find out what happened to his infant sister after she was born at St Mary's mother and baby home in Tuam, Co Galway.
Peter Mulryan, whose infant sister Marian Bridget Mulryan is believed to be among 796 children recorded as having died in Tuam between 1925-61, was too unwell yesterday to attend court.
But he wants Tusla to look at the material it has "and see what happened to that little girl, did she die, was she trafficked or is she buried in the pit", his solicitor, Kevin Higgins, said.
Mr Higgins also said he considered an April 9, 2013, letter from Sr Marie Ryan, leader of the Bon Secours in Ireland, demonstrated that the order knew more about what had happened to children who died there than was indicated in a letter of February 15 last.
Mr Higgins told the court he considered the letters showed Sr Ryan, "as is the norm for the Bon Secours sisters", "is lying through her teeth" and indicated the order knew "a lot more" more in 2013 and knew "where the babies are buried". Mr Mulryan (73), of Derrymullen, Ballinasloe, wants leave to bring judicial review proceedings against Tusla aimed at getting any material that exists concerning his infant sister, who was recorded as having died in February 1955 nine months after her birth at the home.
Tusla has said it has given Mr Mulryan any material it is aware of and has also made the records held by it available to the commission of inquiry investigating the Tuam home.
Mr Higgins said Mr Mulryan was too unwell to inspect the material on the date offered.
Mr Justice Richard Humphreys had adjourned the leave application several times to clarify exactly what orders were being sought.
He also directed Tusla to write to the Bon Secours order, which operated the Tuam home, asking whether it holds any burial records and, if any records existed at some stage, were they destroyed.
During exchanges with Mr Higgins, the judge said the grounds for judicial review were "a bit thin".
Mr Higgins said it was "most unfair" to tell him that now, the sixth time the matter was before the court.
The judge said he did not accept that and it was for the solicitor to get his papers in order. He adjourned the matter for a week to allow Mr Higgins to prepare an amended statement of grounds.