A 35-year-old man has been charged in the Netherlands in connection with the suicide in 2012 of Canadian teenager Amanda Todd, who was bullied online.
The unnamed suspect was charged with extortion, internet luring, criminal harassment and child pornography, Canadian police say.
Suspected of numerous other abuse cases, he has entered no plea.
Ms Todd posted a video before her death where she told how she was blackmailed into exposing herself online.
After pictures were posted on Facebook, an online bullying campaign began and the 15-year-old from British Columbia eventually killed herself.
Her story made headlines worldwide and her video, which contains images of self-harm some readers may find distressing, has been watched millions of time.
On the basis of materials seized, the detainee is also suspected of dozens of cases of online abuse in the Netherlands, the UK and the US, the Dutch newspaper Omroep Brabant reports.
Carol Todd, Amanda's mother, thanked police at news of the arrest, saying: "This is truly a day we have been waiting for."
'More than one'
The suspect, who was arrested in January, made his first court appearance in Amsterdam on Wednesday, at which his detention was reportedly extended for three months.
"Today marks a major milestone in our investigation," said Inspector Paulette Friel of the Royal Canadian Mounted Police. "A suspect has been identified, he has been arrested and he has been charged."
The suspect is said to have been living alone in a holiday home in the Netherlands town of Oisterwijk.
"The suspicions against the man are that he approached underage girls via the internet and then seduced them into performing sexual acts in front of a webcam,'' Dutch prosecutors said in a statement, quoted by AP.
"He is suspected of subsequently pressurising them to participate in making new material."
Suspected targets include men who were allegedly convinced the man was an underage boy and were persuaded into performing sexual acts on camera.
His lawyer, Christian van Dijk, said: "Prosecutors seem to think they have a big fish here, but if I see the evidence, it's not much. Lots of references to IP addresses and such."
He added: "He seems like a decent person, a young good-looking man who is easy to speak to."
Carol Todd told Canada's Globe and Mail newspaper she believed others were involved in the abuse too.
"I don't want everyone to get so hyped up that this is it, that this is the end," she said. "I don't think in my heart that this is the end. It's the start of it. There's more than one person in those chat rooms. There are more people responsible for extorting [Amanda]."