Thomas Lindsay Gordon (62) repeatedly targeted the victim over 11 months and was only stopped when she summoned up the courage to tell a family member, the Dunedin District Court heard this month.
He was interviewed by police on December 1 last year and made no confession but four days later officers found him drunk in an Ashburton cemetery.
Beside him was a courier bag addressed to the Dunedin police, containing court documents and a handwritten statement which made various admissions about his conduct.
Gordon later pleaded guilty to two counts of sexual conduct with a child as well as sexual violation by unlawful sexual connection and possessing objectionable publications.
The court heard from several of the victim’s family members, one of whom described Gordon as "a wolf in sheep’s clothing".
The girl’s mother said her daughter had been robbed of her confidence.
"I notice the sadness in her almost every time we talk," she said.
"You exposed her to the cruelty and darkness of the world."
The victim’s father said the disclosures of the sex attacks had "shaken the foundations of who I am".
"The impacts will stay with her forever ... I worry about all the ways this will affect her in her life," he told the court.
"I don’t know if I’ll ever again feel like I’ve been a good father to [her], knowing I wasn’t able to protect her."
When police raided the defendant’s home, they seized 16 electronic devices, including computers, hard drives and cell phones.
In total, across six devices there were 3326 illegal videos, the majority of which fell into the most serious category (depicting penetrative acts).
Forensic analysis revealed Gordon used an anonymous file-sharing platform to download vast quantities of child-abuse material.
His main method of storage was a desktop computer and police found he had even arranged the haul into eight explicitly-titled folders.
Gordon had been amassing the videos since March 2017, investigators discovered.
Court documents describe some of the content — featuring children as young as 4 — but the detail is too graphic for publication.
When Gordon was interviewed by Probation before sentencing, he said the victim became used to the abuse he perpetrated but on the last occasion he saw the fear in her eyes for what was to come.
Counsel Sarah Saunderson-Warner said her client was motivated to undertake specialist sex-offender treatment in prison.
The court heard he had only a driving conviction to his name in the last 40 years.
Gordon offered $20,000 to the victim and Judge David Robinson accordingly made the order for emotional harm.
The defendant will be automatically added to the Child Sex Offender Register.
