By Tracy Neal, Open Justice reporter of 
Finn Cottam was sentenced in the Nelson District Court to seven years in prison for his sustained, violent and lengthy campaign of online sexual abuse against women. Photo: Open Justice/ NZME - Tracy Neal
An online predator who terrorised his victims evaded capture for years until he made one small mistake.
Police would not say what that was, but it was enough to lead them to Finn Cottam, who this week was sentenced to seven years in prison for the online abuse against targeted victims, which the Crown described as a "sustained campaign of sexual terror".
The "tech-savvy computer operator" took images off women's social media accounts and manipulated them into "graphic and repulsive" pornographic material before threatening to distribute it if his wishes were not met.
The officer who led the investigation, Detective Douglas Nuku of the Marlborough Child Exploitation Team, told NZME the investigation was not easy, but the outcome meant it was the most satisfying he had worked on in more than 20 years in the police.
"A sophisticated response was required to expose this online predator and the sick crimes he was committing.
"It took a complex investigation and nearly two years of work until we were able to charge Finn Cottam and get justice for his victims," Nuku said.
The seeds of the offending dated back to 2013, took hold in 2015 and continued until his arrest in 2022.
He avoided detection by using a large number of encrypted email addresses, which masked content from the service provider.
In many cases, he knew the victims, but they did not know who the perpetrator was, or why they had been targeted.
Contact with identified victims was of a "grossly sexually explicit" nature that was degrading and graphic, Judge Jo Rielly said, while adding that some of the child exploitation material was too harrowing to read in court.
One of the victims told the Nelson District Court at sentencing she feared for her safety everywhere she went and that the discovery of her images on "disgusting" websites would remain with her forever.
"It will always haunt me," she said in her victim impact statement.
Cottam visited websites only available on the dark web to access objectionable material and to disguise his physical location.
He also used multiple VPN applications to disguise his IP (Internet Protocol) address and installed a program known as VeraCrypt on his computer to create encrypted and hidden storage caches.
When Cottam was eventually traced to a property in Motueka, he was found with more than 8000 objectionable images and videos, including child exploitation material, on multiple devices he owned.
Nuku said Cottam "worked in the shadows", believing the dark net and his use of Tor browsers would protect both him and the horrific campaign he was waging.
Tor browsers prevent someone watching a user's connection from knowing what websites are being visited.
Nuku said online crimes were "incredibly difficult to investigate", but three determined investigators "pored over every part of the offender's digital footprint" in an effort to stop him.
After reviewing "thousands and thousands" of data points, police found that Cottam had made one slip-up that led them to him.
"We can't detail the specific point that revealed him as the offender, but it was significant enough to identify him," Nuku said.
He credited the victims for their incredible bravery in coming forward and providing vital information that helped stop Cottam, but the work was far from done.
Nuku said online crime was a growing problem and with the digital world evolving every day, police knew Cottam was not the only offender of his type.
"There are other people in our communities committing the same crimes against others who they befriend, manipulate and blackmail.
"These offenders cause catastrophic damage to people's lives and go to extensive lengths to hide their crimes, which adds to the complexity of our investigations."
Staying safe online
Nuku has urged parents and guardians to talk to their children to ensure they know they can get help if needed.
"Talk with your children about the risks of sharing information and photos with people they don't know.
Police "strongly advised" against giving in to threats or demands; most offenders did not follow through on threats.
Police advise "block, deactivate and report sextortion".
Collect as much identifying data as possible - social media account names, bank account numbers, wallet addresses.
Report sextortion via 105, or file an online report to netsafe.org.nz.
Netsafe can assist in the removal of intimate images through takeitdown.ncmec.org or stopncii.org.
NZ website keepitrealonline.govt.nz has resources about keeping safe online for children, parents and educators.
*This story originally appeared in the New Zealand Herald.
Photo: Open Justice
