Asked what the tipping point to Parker's offending was, Detective Mark Dalzell, head of the police child protection unit in Far North, said: "The absolute courage shown by one boy who in my view is an absolute hero who without any support by any other complainants came forward to talk to us about what was happening, he was then interviewed, that interview formed the cornerstone of our investigation and it progressed from that point."
Parker, 38, was sentenced on 74 charges of various sexual abuse of 29 children spanning up to 13 years when he committed in excess of 300 offences.
The former deputy principal of Pamapuria School near Kaitaia held his head in his hands throughout the sentencing and wept when the victim impact statements were read out by some of his victims and their families.
A second courtroom was opened to stream the hearing live on a big screen to allow members of the public and media who could not fit into the main courtroom to witness the day's proceedings.
Crown solicitor Mike Smith said Parker's actions came to the fore entirely as a result of courage shown by his victims alone.
"When they spoke out did he finally accept what he did? It's their bravery and their bravery alone," he said.
Parker's lawyer, Alex Witten-Hannah, submitted that a long but finite sentence would be sufficient for his client to undertake the necessary rehabilitative measures before his integration back into the community. He said Parker offered his heartfelt apology to all those affected by his actions.
He said none of his victims was coerced into sexual acts and that Parker didn't indulge in his sexual gratification every time he was told to stop.
Even though alarm bells began ringing in 2009, he said Parker felt he'd reached a point where he couldn't stop his sexual deviancy problem and had no one to turn to for help. Justice Paul Heath interjected, saying it was troubling that after being warned by police in 2009 to stay away from the boys, Parker not only continued to offend but his offending escalated until his arrest in 2012.
Anahera Herbert-Graves, of Te Runanga o Ngati Kahu, said the sentence of preventive detention was the best those affected could have hoped for under the law, and pleaded with the victims of convicted paedophiles to seek counselling and move on in life rather than to retreat into their inner shell.
Timeline of events
1998 - Abuse started. Police warn Parker but no action taken.
March 2009 - A victim goes to police but later retracts his statement.
July 13, 2012 - Parker arrested on sex charges involving 15 young boys.
July 14 - Parker confesses to his crimes.
August 22 - Pleads guilty in the Kaitaia District Court to 49 charges of sexually abusing the boys.
September - Education Ministry begins investigation into Parker's actions and how it continued for so long.
September 17 - Kaitaia's clergy join with pupils, parents and friends of Pamapuria School for a service of rededication, marking a new beginning after the devastation brought upon the school and community by Parker.
November 25 - Charges relating to eight more victims laid by police include eight of performing an indecent act on a boy under 12 years, four of an indecent act on a boy aged 12-16, one of indecent assault on a boy under 12, four of indecent assault on a boy aged 12-16 and four of sexual violation.
April 10, 2013 - Parker's case transferred to the High Court by the Kaitaia District Court after he pleaded guilty to 25 more charges.
May 2 - High Court callover. Crown prosecutor Mike Smith informs the court he'll seek preventive detention for Parker.
August 15 - Parker is sentenced to preventive detention.