Peter Mulryan (73) discovered he had a sister only two years ago - and now his greatest wish is that she is still alive so they can make up for decades of lost time.
Mr Mulryan, from Derrymullen in Ballinasloe, Co Galway, is now ill with cancer and said he had no access to files about Marian Bridget Mulryan.
It is thanks to Catherine Corless, the Tuam historian, that he found out his sister was listed among those who had died at just nine months of age and was buried in the nearby grounds.
He has a birth record, a death certificate and the cause of death, convulsions.
But because the records are so unreliable he clings to the hope that she may have been adopted and that is why he desperately needs to see her file.
Mr Mulryan, who is currently taking a High Court case, said yesterday he expected it to continue for several more days.
"I am looking for the file and have been refused it."
He wants to know if the little girl who died, was she "trafficked" or buried in "a pit".
His mother Delia spent more than 30 years in the Mother and Baby Home in Tuam and he himself was "boarded out" to a family as a child.
It was a tough life and one that still brings back many sad memories.
Mr Mulryan went on to have a happy marriage to wife Kathleen and they have seven children.
He recalled the sense of shame his mother had, which she carried with her throughout her life.
But the revelations about the mother and baby homes, and the emergence of the truth from the days of dark shadows, have brought a new sense of relief and freedom.
Mr Mulryan first went to the Tuam home with his mother in 1944 and he was boarded out when he was just four years old.
Tusla has claimed it has given him all the information it has.
It said it had also made records available to the Commission of Investigation into Mother and Baby Homes.
Around 30,000 children were informally boarded out between 1922 and 1952 at the rate of around 1,000 a year.
Many families took in children as part of the arrangement and received a monthly payment from the local authority.
There are few records of the boarding-out system and there were hardly any inspections.
Mr Mulryan said he would dearly love to find his sister if she was in fact alive.
He wonders if she might be in the United States, where she could have been adopted by another family as happened to so many other children.