The global paedophile ring that allegedly involved a 42-year-old Kiwi man was brought down by a simple photograph of a little boy getting a henna tattoo at a US zoo.
The little boy was on holiday with two men who claimed to have adopted him from a Russian woman.
They were Queensland couple Peter Truong and Mark Newton.
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Kiwi extradited to Oz charged over global child sex offending network
It later emerged that they had paid US$8000 for the little boy and travelled the world with him, farming him to a network of paedophiles to sexually abuse.
In 2014 Australian current affairs programme Four Corners aired a story on the case which revealed how the men were caught and their "son" rescued.
Detective Inspector Jon Rouse of Task Force Argos - a specialist unit within the Queensland Police responsible for investigating on-line child exploitation and abuse - told Four Corners that Truong and Newton "knew their craft" when it came to their offending.
"You know, they were technically capable men," he said.
"They knew what they were doing online. They knew how to use the internet. They'd been using the internet for a very long time.
"They knew how to protect themselves. They maintained their communications largely within their identified group of safety."
Truong's filthy network included IT professionals and encryption gurus around the world.
It emerged that they had taken their "adopted son" to 30 countries within six years and
allowed men to sexually abuse him.
The little boy's passport had been filled by the time he was 3.
Four Corners revealed that often, the boy was handed over for sex in exchange for his abusers paying Truong and Newton's travel and overseas entertainment expenses.
The abuse of the boy was often filmed and shared within the global paedophile network.
Eventually, Rouse and his team would make a connection between the abuse footage and the Cairns couple.
Their sick scheme stated to unravel in mid-2011 when one of the men within the network had his Idaho home raided by police.
A set of DVDs was found showing the man sexually abusing a number of children.
He admitted to police he was part of an online chat group where like minded men talked about abusing children and shared videos and images.
He gave police the names of some of the chatroom users, which led to further arrests including Thomas Vaughn in Anderson Indiana.
At his home, police found images of a young boy being sexually abused by an adult male.
Both of their faces had been cropped out but the boy had a distinctive henna tattoo on his chest and a mole on his tummy.
It wasn't until the Argos team obtained family photos from Truong and Newton that the young victim was identified.
Photos dated April 2011 showed Truong and Newton's son getting that exact henna tattoo at a zoo in North Carolina.
"The dead set immediate giveaway was the tattoo," Rouse said.
"There's a henna tattoo, very, very particular.
"You put it all together, it's definitely our boy ... that was it, case closed."
Truong and Newton were arrested and tried in the US on a raft of child sex offences.
Newton was sentenced to 40 years in prison.
Truong, after receiving a discount for supplying passwords to encrypted hard drives, thus helping secure the arrest of other international paedophiles, was sentenced to 30 years.
Rouse said during the examination of devices belonging to the men information was obtained enabling investigators to identify the 42-year-old New Zealand man.
It is alleged the Kiwi engaged in the sexual abuse of Truong and Newton's child, and taken hundreds of indecent images.
"This arrest closes the final chapter on a protracted and difficult investigation that has resulted in the arrest of members of a child sex offender network that spanned the globe," Rouse said.