Inside the police units that hunt down online paedophiles

The team of law enforcement officers, who have come from around the world to work at the Australian initiative, spend hours looking at images and videos of child sexual abuse.

Rather that focus on the child themselves, the investigators are looking at the background for clues that might indicate where in the world that child is - and where this crime took place.

It could be the logo on a soft drink can perched on a table, an unusual patterned doona or the language being spoken by someone on a radio playing in the background - anything that could help narrow down the search.

Read more: Wollongong wife speaks out after finding husband's stash of child porn to police

Other investigators spend time online pretending to be children, trying to entice a paedophile to try and groom them.

Another job will be to actually pretend to be a paedophile themselves. In those instances, the team has managed to track down and arrest the administrator of an online forum catering to child sex offenders.

Then - in a move that is controversial to some - an investigator takes on the role of the administrator, which means having to prove to other members of the forum that they share the same interests in children.

Detective Inspector Jon Rouse admits it's not an easy job to do.

"The first time I did that was 2001-2002 where I was actually purporting to be a child sex offender engaging with other child sex offenders," Insp Rouse said.

"It certainly is a very challenging psychological effort for all of the investigators that do it because ultimately you are having to convince another entity that you have a similar interest in children. Personally I found it challenging because I had a very young daughter. She was five or six years of age at that time, so you're talking about having a sexual interest in a child of a similar age and you're dealing with content you're seeing images and material of a similar age - so I think you can understand that's quite hard."

Insp Rouse began working in child protection in 1996 as part of the Queensland Police child abuse crime group. From there he established Task Force Argos and now oversees that group's actions under the auspices of the Australian Centre to Counter Child Exploitation (ACCCE).

One method of dealing with the thousands of images that flood into the ACCCE is a trick Insp Rouse said he learned from a Swedish police officer. Those images represented a moment in time when a horrendous crime took place so, as a police officer, they treat them as a crime scene.

"It's very different from your traditional crime scene because with a homicide, you turn up, there's the house, the crime scene tape is out, the fingerprints and scientific goes through.

"We actually have to find the crime scene. Where in the world is it and then work our way back from the image so we get the evidence. But we have to find out where it occurred, so then to get your mind into the right frame you will listen to the audio - but you're listening to the audio for clues. All of it is focused on trying to find the child."

There are psychological support services in place for investigators and Insp Rouse said people are cycled through the various roles in the task force to limit the mental toll. People are even able to go off for three months and investigate something else, in the knowledge that their chair will still be there when they return.

While, for a lot of people, the tasks the investigators undertake would be too much to bear, Insp Rouse pointed out that trauma is part and parcel of a police officer's job.

"The balance you've got to keep in this conversation is the work of law enforcement holistically is about trauma," he said.

"When we are there it's because something's happened. It could be a fatal traffic accident - those are some of the worst things that anybody has to see. Children get killed in car accidents and our police officers have to deal with that.

"Homicide scenes are equally horrendous things to be confronted with. I went to a drug overdose where a 17-year-old girl was bawling her eyes out because she woke up next to her 18-year-old partner who OD'd on heroin and she woke up next to him.

"You see and deal with trauma all of the time as a police officer - this is no different. It's just a different specialist field of investigation. Police officers globally deal with post-traumatic stress from the work they do, we are no different."

A large chunk of the work comes from the 20,000 or more cyber tips a year that come into the ACCCE from around the world. Many of those come from social media giants like Facebook and Instagram, who are reporting illegal use of their platform.

Some of the photos that come in aren't taken by child sex offenders, but by the children themselves - often at the request of someone they are speaking to online.

"The biggest challenge we're facing here right now is self-produced content," Insp Rouse said.

"It's kids activating their devices and whether they've been groomed and are being exploited or they think they're talking to a 13-year-old, they're producing content and that content is ending up here at the ACCCE."

For parents, Insp Rouse said it was vital to know what social media apps their children were using, even if it means sitting down with them and going through their friends lists.

"Now the internet is fully mobile and if you don't understand the apps that your child's using, there's a lot of child sex offenders that do," he said.

"I would be mortified if parents had an attitude that it wouldn't happen to me, because it probably already has and you don't even know.

"If my little one was now seven or eight, bedtime would be 'surrender your device' time - the technology stays with me until the morning when I give it back to you.

"That would be the first thing I'd be doing if I had a young child now."

The Children in the Pictures, a documentary on the workings of Task Force Argos, airs on SBS at 8.30pm on Sunday, October 24.

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