An American child abuse watchdog made more than 4000 referrals of web pages suspected to contain child sexual abuse images or videos to New Zealand enforcement agencies last year.
It's believed to be the highest ever number of annual referrals from the US-based National Centre for Missing and Exploited Children (NCMEC) to New Zealand investigators.
The data included a "spike" related to a locally-produced video, depicting New Zealand high school students engaging in explicit sex, which went viral on social media.
Globally, child sexual exploitation offending is thought to have worsened during the Covid-19 lockdowns as predators spent more time at home on computers and the "dark net".
New Zealand officials admit the extent of the problem is "alarming". Children's increasing access to internet-capable devices - often provided by oblivious parents - is blamed for the growing number of cases.
And despite investigators identifying about 50 New Zealand child exploitation victims each year, there are fears "vast" numbers of offenders here are going undetected.
Department of Internal Affairs (DIA) deputy director of digital safety John Michael says child sexual exploitation crimes have disastrous effects on young victims.
But the crimes were often difficult to identify because the tech-savvy offenders use encrypted platforms to share files.
"I've heard commentary that it's 'just a photo'. But what that doesn't show is the long-term and sometimes permanent harm that's done to those victims. Some of those victims don't ever get over it."
The US referrals resulted in a raft of prosecutions last year by DIA, police and Customs.
In December, Northland man Brent James Ruddell, 34, was jailed for more than 15 years on 72 charges after footage found on seized electronic devices revealed evidence of his own sexual offending against children as young as 2.
Ruddell's arrest stemmed from an NCMEC referral after he uploaded two child sex images onto a popular social media platform.
He was prosecuted after an investigation by Taskforce Ruru – a joint victim identification agency made up of specialists from Customs, police and DIA.
And on Friday, Aaron Hutton, 36, was jailed for five years for trying to buy a child with bitcoin on the dark web to sexually abuse, under the username Kiwipedo.
He was caught communicating with covert investigators who later used a tracing tool to identify his Auckland computer before executing a search warrant.
Michael said coordinated criminal investigations into the US referrals were catching offenders and identifying child sex victims both here and overseas, preventing further abuse.
Victims ranged from naive teens uploading compromising selfies to the internet, to young children who had been physically abused by paedophiles then video of the abuse shared online.
And while New Zealand punched above its weight internationally in terms of enforcement, Michael admitted it was impossible to know how many sexual predators were operating undetected - many of whom had no criminal history and good jobs.
"Online groomers may offend against 30 or 40 victims and never come to the attention of law enforcement agencies because there's no complaints.
"There are definitely children being groomed online who have taken imagery and sent that to their groomer.
"Very occasionally we see the imagery of children in New Zealand being circulated overseas."
DIA figures released to the Herald under the Official Information Act show it has received nearly 15,000 NCMEC referrals since 2016.
About 450 suspects have faced court since 2015 for possessing, making or distributing objectionable child sex material, sexually grooming minors on the internet, blackmail and indecent communication.
However, Customs officer Kesta Dennison believes many offenders are avoiding prosecution.
In a thesis on whether New Zealand enforcement agencies had sufficient resources to tackle the online sexual exploitation of children, she said prosecution figures suggested investigators focused on those cases with a high likelihood of conviction, "when in fact, with only a few investigators, it is likely that there are a vast number of people who are not being prosecuted".
Michael said many of the referrals stemmed from international electronic communication services like Facebook or Twitter, which were required under US Federal law to report suspect web pages to the NCMEC's CyberTipline.
NCMEC staff established each referral's country of origin then sent the referrals direct to the relevant nation's enforcement agencies.
In New Zealand, DIA is the "triage point" - responsible for assessing those referrals then forwarding them to specialist child exploitation units at DIA, police or Customs.
Michael said the DIA's digital safety group team worked tirelessly to counter digital violent extremism and unsolicited electronic messaging.
It had investigated hundreds of NCMEC referrals since partnering with the US watchdog in 2010.
But the volume of work and constantly changing trends put "significant pressure" on resources, he said.
A new concern was the risk of major social media companies moving to "end-to-end encryption". It meant evidence of online grooming or sharing of objectionable child abuse material could be lost to enforcement agencies, making it harder to identify and protect victims, Michael warned.
"There's a lot of offending out there. These offenders are very tech-savvy, use encryption and anonymous platforms that we may not detect through traditional means.
"A lot of these people don't have any history, they're not known to police and have good jobs."
Globally, the NCMEC had made nearly 17 million referrals in 2019, of which New Zealand accounted for 0.02 per cent.
Last year's New Zealand referrals included an August spike related to a locally-produced video that went viral on social media among New Zealand secondary school children. The video was identified by NCMEC and reported to DIA, and police were eventually involved.
Michael said it depicted explicit sex among teenagers.
"Sadly that sort of content is all too common."
An Interpol report released in September on the impact of Covid-19 lockdowns on child exploitation and abuse found an increased use of the dark net by offenders and more sharing of files on peer-to-peer networks.
It also found a jump in "self-generated material" by victims on the clear net but a decrease in travelling sex offenders and child trafficking.
And while thousands of referrals had been made to New Zealand authorities in recent years, many of the cases were closed because of insufficient evidence to proceed with an investigation, or the images not being classed as objectionable under New Zealand law, Michael said.
Simon Peterson, Chief Customs Officer - Child Exploitation Operations Team, said identifying and protecting children was the number one priority for law enforcement agencies that investigated this type of horrendous crime.
"Sadly, we're seeing that there is an increasing amount of crossover between those who deal in child sexual abuse material and those who physically offend against children."
Last month's Northland sentencing demonstrated the strength of a joint-agency approach to stopping child sexual exploitation and protecting victims, Peterson said.
"Child sexual exploitation images and videos are often crime scenes of abuse occurring at the time, sometimes in the most horrible ways imaginable. It's therefore inaccurate and demeaning to refer to such publications as child pornography, as these children are re-victimised every time the images or videos of their abuse are viewed."
Roll of shame:
• Former North Shore community board chairman Martin Henry Lawes was jailed for four years and six months in September 2018 after paying more than $100,000 over 10 years to access livestreamed sex shows filmed in Asia.
• Nigel Maurice Urwin, 43, was jailed in 2019 for five years and nine months for the distribution and possession of objectionable material.
• Former cheerleading coach Nikola Marinovich was jailed last September for three and a half years for possessing, making and distributing graphic child abuse material after a tip off from a Canadian social media platform.
• Northland man Brent James Ruddell, 34, was jailed for more than 15 years in December last year after footage found on seized electronic devices revealed evidence of his own sexual offending against children.
• Aaron Hutton, 36, was jailed on Friday for five years for trying to buy a child with bitcoin on the dark web to sexually abuse, under the username Kiwipedo.
Tips to keep children safe online:
• Talk to children about risks of online activity and how to report harmful content.
• Manage screen time and understand how and why children are using the internet.
• Check movie, TV and games ratings to ensure they're suitable for your child's age.
• Check your internet service provider's privacy settings and parental controls.
• Check privacy settings on children's social media accounts.
• Follow people your children have met in person and unfollow "unofficial" pages.
• Turn off location sharing on social media platforms and review your child's basic information and profile picture.