Christian van Dijk is unflappably Dutch. He wears slim European suits tailored to his slender runner's frame. His hair, thin on top, is a carefully managed stubble. When a visitor spills a full cup of coffee on his company furniture, he just smiles and continues with a story as if nothing happened.

But seven red binders sitting upright on his desk pose a clear source of consternation. They contain thousands of pages, each emblazoned with swarms of disorderly digits, impenetrable to all but the most tech-savvy of readers.

Mr. van Dijk has read and reread each binder several times as he prepares to defend Aydin Coban, the 35-year-old Dutch man charged in relation to the online torment of Vancouver teen Amanda Todd, but even he strains to describe exactly what all the numbers mean and how they fit together.

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"In the beginning, none of this made sense to me," he says, thumbing through the pages in his Utrecht office. "There are so many numbers, abbreviations and difficult words. Now I understand it, but I need the help of a computer expert to help make sense of everything."

He's hardly alone in his puzzlement. The British police agency involved with the case called it "extremely complex" and alleges Mr. Coban used some of "the most advanced techniques available to target his victims and in an attempt to hide himself."

But somewhere in the digital labyrinth is the story of two lives, both lived largely online, that entwined briefly and, for one, ended tragically. Amanda Todd sought affection and treated her onscreen realm like a stage and a confessional. Aydin Coban, according to police, traded in deception and anonymity, something he would succeed at for years before his arrest in January.

Both online and around the southern Netherlands city where he grew up, the name Aydin Coban draws little recognition. Until last year, he was an unknown entity among police as well. The Globe and Mail has learned that it was the security team in charge of safeguarding the world's largest online social network, Facebook, that finally led investigators to Mr. Coban.

"I don't think the police made this case," says Mr. van Dijk, staring at evidence bearing Facebook Security letterhead. "I think Facebook made this case. They put it all together."

Facebook declined to comment on any involvement in the Todd case, offering only a general statement. "In the rare instance when this illegal behaviour is detected in our community," says a spokesman, "we have strict guidelines for working with law enforcement to bring suspected criminals to justice and keep Facebook a safe place."

If Mr. Coban committed the crimes of which he's accused in Holland – production and distribution of child pornography, indecent assault, fraud, computer intrusion and others – the involvement of Facebook in his arrest would seem fitting. It was on the social network in late 2010 that Amanda Todd's life first began to unravel.

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She was in Grade 7 at the time and lived life through her laptop, singing Adele and Christina Aguilera songs for friends and admirers, sometimes dancing. She was playful, talkative. During one ill-fated session in her webcam chat room hosted on BlogTV, a user convinced her to expose her breasts. Somewhere among the more than 150 users in the chat room that day was a 'capper'.

Cappers are an insidious strain of online lurker who lie in wait in chat rooms and social networks and incite other users to expose flesh so they can save the images for posterity. They use the saved image to extort more images or information or even money from their targets. Some do it for a thrill, others for money, yet others for bragging rights among the tight-knit capper community. On this day, someone capped Amanda's topless image. Soon the images were posted to a porn site and a link sent to her Facebook friends.

Over the next two years, the tormentors would return. The documents on Mr. van Dijk's desk point to one Facebook user in particular, Tyler Boo, who threatened to distribute more images of her unless she provided more "shows" onscreen.

By the fall of 2011, partially nude images of Amanda re-emerged online. The RCMP warned her parents she should be kept off Facebook and other sites for her own safety. Their restrictions didn't stick.

Another year passed before Amanda let the whole world in on her plight. In a nine-minute YouTube video, she outlined her torment on a series of hand-written placards, a visual trick reminiscent of Bob Dylan's video for Subterranean Homesick Blues, considered the forerunner of the modern music video. In writing, she told her story, including details of one attempt at suicide by drinking bleach.

The video drew a moderate crowd by YouTube standards, most of them offering sympathy. But it wasn't enough to buoy her flagging spirits. On Oct. 10, 2012, she took her own life.

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In the weeks that followed, her story became international news. The Coquitlam, B.C., RCMP assigned 30 investigators. A small army of hackers, independent web researchers and a journalist for Vice.com exposed the shadowy world of cappers who pursued images of Amanda and other vulnerable girls.

"Looking back, there were a few clues," says Jen Sadler, one of dozens of independent sleuths who took up the cause of finding Amanda's tormentors. "In some of the chat logs people dug up there was someone with the initials 'AC' talking. And there was a Netherlands connection with another girl who faced a similar situation."

But at no time did the name Aydin Coban or the bucolic Dutch town where he resided ever enter the frame.

The Todd case had gone cold for a year by the time the Dutch National Police Agency zeroed in on a cluster of 14 drab bungalows in the south of the country. The Bungalowpark De Rosep is a five-minute drive from the picturesque town of Oisterwijk, 110 kilometres south of Amsterdam, where noisy café tables spill out across the sidewalks and a Ferrari sighting is not uncommon. It has the feeling of cottage country, a place where people can commune with nature among the maze of local walking and biking trails.

If Mr. Coban sought privacy, this park was the place for it. Broad-leafed trees and a barbed-wire fence obscure any view of the brick bungalows from the road. Unfamiliar visitors are provided a cold welcome by the park's owner. The individual cabins are arranged along a narrow road, barely wide enough for a sputtering Volkswagen Golf that coughed blue smoke as it dieseled by on a recent weekend afternoon.

Most of the tenants are guest-workers from Hungary, Poland and Slovakia, some employed at a nearby meat plant. Each cabin runs between $1,000 and $1,500 a month, according to Jacob, a retired Dutchman who has lived in the park for several years and keeps his bungalow in immaculate condition. An avid hunter who has roamed as far as Smithers, B.C., to bag a grizzly, Jacob keeps close watch on all movement around the park. But he never once saw Mr. Coban.

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"He's a big mystery to all of us here," he said. "We all talk around here, but no one knows him. And no one saw him get arrested, but we know it happened here."

Further down the path, a Slovakian tenant says he saw Mr. Coban, but never spoke to him. "He didn't talk to other people."

At the main office, the owner tries her best to shoo away inquiring journalists by insisting Mr. Coban didn't live at De Rosep. "You have the wrong place," she says. Presented with contradicting testimony from her own tenants, she relents. "Yes, okay, he did live here, but I never saw him, never talked to him, never dealt with him. That's all I know."

Born in Holland, Mr. Coban's parents emigrated from Turkey and live in the area around Tilburg, Holland's sixth-largest city, nine kilometres west of Oisterwijk, according to his lawyer. He had no spouse or children and didn't attend a mosque, judging by the lack of name recognition at any of the area's major mosques.

Back in Oisterwijk, a Turkish-Dutch resident who requested his name not be used said he once met Mr. Coban. "A friend of mine knew him," he says. "He is not really someone special. He's not very charismatic. An ordinary man."

While his physical profile was going unnoticed around Oisterwijk, Mr. Coban's digital incarnation was attracting attention with Facebook's security unit in Menlo Park, Calif. The security unit maintains algorithms designed to detect and delete fake accounts and watch for suspicious activity. In a 2012 Forbes profile, the head of Facebook security, Joe Sullivan, said that the algorithm red flags anyone who sends more than 80 per cent of their friend requests to females, or users who constantly change their birth date.

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According to Mr. van Dijk's interpretation of the evidence, Facebook noticed that a single IP address – the unique locator number for each device connected to a computer network – was setting up dozens of Facebook accounts and accumulating friends and photos at a rapid pace.

"Facebook is saying a lot of accounts were made – 20 or more – and from those accounts people were getting connected very quickly, and then alarm bells ring in the offices of Facebook," Mr. van Dijk says. "They are the ones who put together all the names and the aliases and they said the person should be on this specific IP address in Tilburg."

Facebook investigated before preparing a security report for U.S. authorities, who passed it along to the Child Exploitation and Online Protection Centre attached to the U.K. National Crime Agency. By May, 2013, the report was in the hands of Dutch police, who launched an investigation four months later. The Dutch focused particularly on one IP address in the report – 77.165.109.4 – which they traced to the Tilburg area, according to Mr. van Dijk. That information led Dutch authorities to the cabin, where they arrested Mr. Coban in January. He now sits in prison, Penitentiaire Inrichting Nieuwegein, just outside Utrecht, waiting for his next court date, June 26.

The connection to the Todd case became more evident to police after they seized a computer and router from Mr. Coban's cabin.

"They are alleging [Mr. Coban] is Tyler Boo," says Mr. van Dijk, referring to one of the aliases known to harass Amanda.

Investigators have also focused on seven MAC addresses – the unique serial number for network devices, similar to a VIN on a motor vehicle.

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Amanda wasn't the only alleged victim. The Dutch Public Prosecution Service alleges there were more extortion victims in the U.K., U.S. and Canada, where Mr. Coban has been charged with luring a child under 18 via computer, extortion, harassment, as well as importing, distributing and possessing child pornography.

The alleged scheme also involved adult men living outside the Netherlands. The prosecution alleges Mr. Coban persuaded men to perform sexual acts via webcam on the belief they were communicating with an underage boy. The men were then blackmailed with threats that the images would be passed on to the police.

So far, the binders on Mr. van Dijk's desk carry little mention of the RCMP, but he expects that to change when a looming extradition request arrives. "Right now I must only concentrate on the case before me," Mr. van Dijk says. "I can't focus on extradition."

He does, however, question how the heavy news coverage in Canada could prejudice any possible court proceedings.

While he wouldn't offer many clues as to how he plans to defend Mr. Coban, he did air reservations about the heavy involvement of Facebook with the investigation. "Who is to say that Facebook did this investigation correctly? We will have to go over all their work."

Some of the police allegations still don't make sense to Mr. van Dijk. Of the seven MAC addresses that appear in the police documents, he says only one was actually found on a device in Mr. Coban's cabin.

What Mr. Coban has to say about all this remains a mystery. A Globe and Mail request to visit him at Nieuwegein prison was turned down. Mr. van Dijk has received specific instructions to keep his biographical details out of the news. How long he'll remain in prison is anybody's guess.

"I expect this to take a long time," Mr. van Dijk says. "It could take a year, two years. It's not a small case."