For 40 years Brendan Smyth used his position in the Catholic Church to target, groom and sexually abuse innocent young children.
The Church was well aware of his crimes, but rather than address them he was simply moved from diocese to diocese.
A "very intelligent" man, he "used his intelligence and cunning to intimidate and oppose those who confronted him," revealed Fr William Fitzgerald, of the Norbertine Order, of which Smyth was a member.
"He was able to silence and ridicule those who would confront him," Fr Fitzgerald told the historical abuse inquiry yesterday.
Smyth was born in west Belfast on June 8, 1927. According to Smyth's medical notes he said that his family were poor, but were secretive about their lack of wealth. His father worked as an auctioneer.
Smyth had asthma as a child and was not as athletic as his brother at school.
He left school aged 18 and joined the Norbertine Order in 1945. He was ordained on July 31, 1951, at the age of 24.
What followed was one of the most horrific abuses of trust ever seen within the Catholic Church in Ireland.
While the full scale of his crimes may never be known, Smyth once admitted he may have abused hundreds of children. He failed to accept the devastating impact his crimes had on his victims telling police after his arrest in the 1990s that in some cases the abuse "hasn't done any harm".