Gardaí were aware of the activities of notorious paedophile priest Father Brendan Smyth as far back as the early 1970s, an inquiry has heard.
Documents shown at the Historical Abuse Inquiry in Northern Ireland also revealed that a doctor at St Patrick's Hospital confirmed a diagnosis of paedophila in 1974.
Smyth, who was at the centre of one of the first clerical child sex abuse scandals to rock the Catholic Church in Ireland, was eventually convicted of more than 100 child abuse charges on both sides of the Irish border in 1994. He died three years later in hospital.
Confidential documents from St Patrick's psychiatric hospital in Dublin revealed that Smyth had asked to be admitted after coming to the attention of gardaí in 1973.
In a letter to an officer at Finglas Garda station dated November 1 1973, Smyth's psychiatrist wrote: "I have been asked to write to you by Fr Brendan Smyth of Holy Trinity Abbey, Kilnacrott.
"He has been a patient under my care for some months and I am familiar with the nature of his problems.
"I am writing to his superiors suggesting that he should have a period of in-patient care in St Patrick's Hospital or in St Edmonds Bury.
"I hope this arrangement will be satisfactory to you and your superiors."
Joseph Aiken, counsel for the inquiry, said Smyth had been conducting a retreat in Finglas in July 1973.
Mr Aiken said: "For some reason Brendan Smyth has asked the doctor looking after him to write a letter to Finglas garda station to say that he is going to be taken in for some in-patient treatment."
The documents, which were only released to the inquiry yesterday despite repeated requests by the Norbertine order over decades, also revealed how Smyth was officially diagnosed as a paedophile in 1974.
A case summary dated February 1974, read: "Psychosexual difficulties for many years. First developed in the Novitiate. A recurring problem, no matter where he has been stationed. His paedophilia has brought him into contact with the police."
The inquiry has set aside a week to examine whether systemic failings allowed Smyth, from west Belfast, to continue offending for more than four decades.
Retired Cardinal Sean Brady - who was a note-taker during a much criticised church investigation into Smyth's deviant behaviour in 1975 - is expected to give evidence today.
The inquiry was also told that Smyth threatened to punch another cleric who warned him to stay away from altar boys.
Fr William Fitzgerald, who served with Smyth at Kilnacrott Abbey in Co Cavan during the late 1980s, described the serial child molester as a scary individual whose notoriety extended across the world.
Giving evidence to the Historical Abuse Inquiry, the 61-year-old Australian also said he had to bar Smyth from church rehearsals with nine altar boys.
"I told him, 'in view of the rumours about you and your sexual activities with children, you will not be anywhere near these kids under my watch'," he said.
"He said 'I'll knock your head off.' I said 'oh make my day you b*****d. I'll knock your head clean off'."
Apologising to the victims, Fr Fitzgerald slammed efforts to stop the prolific paedophile as "pathetic", claiming Smyth's poisonous legacy had forced the closure of Kilnacrott Abbey and destroyed the Norbertine order.
"In Ireland, the word Norbertine means paedophile," said Fr Fitzgerald. "Anyone who knows what the word Norbertine means, they just mark them with the brush of Brendan Smyth.
"The whole order, from the top of Denmark to the bottom of Brazil, has been slashed with the paedophile brush."