Child safety advocates are concerned about Facebook's plans to introduce secret messaging, saying it could be "good news" for paedophiles.
But the social media giant tells Newshub it has no plans to stop - and says it's actually about offering protection from hackers and cybercriminals.
Brent Ruddell will spend 15 years behind bars for offending against five young children.
His horrible crimes were uncovered after a police search warrant in Northland, but he was only picked-up because he used social media to share abusive images.
Ruddell is one of many offenders caught sharing pictures of, or grooming children on social media, but a new plan for the popular Facebook app 'Messenger' threatens to slow authorities down.
"Facebook can currently read your messages on Messenger which means law enforcement and other people can read those messages and see the content that's being shared, after this move that will all be invisible," Netsafe's Martin Cocker says.
Facebook plans on introducing 'encrypted messaging' over the next few years which means only the sender and receiver can see the content of messages.
"The worst-case scenario is the app becomes more popular among people that wish to share child sex abuse material because they feel they can do so anonymously," Cocker says.
Britain's National Crime Agency has already warned Facebook's plans for encryption on Messenger will create a "hidden space" for paedophiles. Australia too is worried about what it could mean.
In New Zealand, Children's Commissioner Judge Andrew Becroft was shocked when Newshub told him.
"Frankly I was immediately concerned because I think in these sorts of decisions children can get lost in the wash," he said.
Becroft said it's essential that officials can be in a position to protect kids, but encryption means they won't even know the crimes are being committed in the first place.
"Children are even more vulnerable more easily exploited and are at greater risk when this happens, and I'm sure if you ask the police it makes their detection job doubly difficult."
Police told Newshub encryption continues to be a challenge and online child exploitation is especially affected by these developments as offenders utilise tools and technology to anonymise and hide their activity online.
Cocker said Facebook knows what the consequences of encryption will be for children, but a spokesperson for Facebook says it's actually about offering protection from hackers and cybercriminals.
"We have zero tolerance for any behaviour that exploits children," they say.
"We already work closely with law enforcement agencies in New Zealand and around the world to report and remove harmful content. We take strong action against any user who shares content that exploits or endangers children, including banning the user and reporting the matter to the relevant authorities. Facebook leads the industry in combating child abuse online and we’ll continue to do so on our private messaging services."
For now, it has no intention of changing its plans.