Chief Customs investigation unit officer Shaun Fujimoto said the three agencies work together to fight child exploitation. They have a motto: "It takes a network to defeat a network."
"Our role in this is obviously to protect New Zealand's borders, which includes the virtual border, from online offending."
Customs officers are able to arrest and prosecute anybody in New Zealand importing or exporting objectionable material. This means their targets include people uploading or downloading the material to or from an overseas site.
Much of the material is found online; numbers of items being brought in and out of the country in hard copies or on electronic devices is dwindling.
This is not a victimless crime.
Figures released by Customs showed 488 items of objectionable material were seized at New Zealand airports in 2013. In mail centres 213 items were intercepted. In 2016, that number was down to 55 for airports and 19 for mail centres.
Meanwhile, online offending continues to grow.
"This is a growing, ever-increasing sort of threat, not only to New Zealand, but globally."
International estimates are that at any one time, 750,000 people are sharing child exploitation material.
Fujimoto emphasised the importance of referring to the images and videos as "child sexual abuse material" rather than the commonly used "child porn".
"The term is outdated and misleading, and it implies there is consent from the child," he said.
We have to be mentally resilient. We have our own coping mechanisms for that.
Each picture or video "shows a child's quality of life horribly damaged or destroyed", and every time the file is shared or viewed, they are revictimised, he said.
"This is not a victimless crime."
The Customs team working on this is a small one, with just a handful of people.
Fujitmoto said there are support mechanisms in place to help staff deal with the horrific material they come across. If they are exposed to it, they are regularly screened and debriefed by a psychologist.
"The mental wellbeing of our staff is top priority for us."
Fujimoto's "bunch of very dedicated, committed staff" have to remind themselves not to let the offending get to them.
"We have to be mentally resilient. We have our own coping mechanisms for that."
They had to stay focused on the job at hand and not let their emotions get in the way of it, he said.
"At the end of the day we're only human, but we just have to view this objectively in terms of we're professionals and we have a job to do."