In the hours after Anders Behring Breivik's massacre of young Norwegians, the internet buzzed with rumours that Islamic extremists were behind the killings.
While in one sense the truth was the opposite - Breivik appears to have been motivated an anti-Islamic ideology - his actions have much in common with those of equally confused young men who have killed at random in the name of Allah.
Many issues must be tackled to prevent future atrocities, but one vexing problem is the role of the internet.
Like many killers in recent years, Breivik's mind seems to have been poisoned online. Sitting behind a keyboard, it is easy to be selective about what information and whose opinions you see, and to be radicalised as a result, especially because the internet allows communities of like-minded people to share their views unchallenged. Internet discussion also allows anonymity and lacks the requirement for listening to others usually expected face-to-face - an ideal environment for extreme views.
At a special Westminster meeting to discuss "Murder In The Name Of God" earlier this year, British attorney-general Dominic Grieve said people can use the internet to live in almost complete isolation from their neighbours, while being "drip-fed the ideas of someone far away in another country."
He warned such isolation fosters radical ideologies and said governments must encourage people to discuss issues in the real world, not a distorted online one.
"The process of debate is not just about imposing the will of the majority on the minority, it is about moderating your views by listening to those of others," he said. "That is the single best weapon we have [against extremism]."
Sadly, high-profile events such as Breivik's shootings and his Olso bomb happen in seconds, while the quiet work of building peace takes years and suffers when such acts are carried out. While security naturally becomes a priority after such events, states must also persist with projects which help create tolerant societies.
One such project is being pioneered in south London, where Lambeth Mediation Service (LMS) is working to bring people of all backgrounds together to discuss issues in the open. The charity is training "Peace Ambassadors" whose role is to bring people from all corners of Lambeth's diverse population to community meetings and then facilitate productive conversations.
"At the moment it's too easy for people of different cultures and nationalities to live entirely separate lives in the same area, without opportunity to interact," said LMS chief executive Jai Jayaraman. "Communities living in isolation tend to blame the people they don't know, so we want to create opportunities to bring people together and facilitate not just conversations, but real dialogue and debate about important issues."
Such schemes help bring people out of isolation to meet their neighbours in person, rather than reading about them online - and it is much harder to hate someone you have actually met. Even in moderate countries like Norway, extreme individuals will sometimes hit the headlines, but liberal societies can reduce the chances by finding ways to reach those who hide in a virtual world where violent ideas cannot be properly challenged.