U.K. prosecutors on Tuesday said a London terror suspect was “brainwashed” by right-wing personalities and online material — including from a Canadian outlet — in the weeks before he allegedly drove a van into Muslim worshippers, killing one.

Earlier this month, a man threatened to shoot CNN employees to fight the network his president mercilessly targets — “Fake news. I’m coming to gun you all down,” a male voice said in a telephone call, according to documents unsealed this week.

And in Canada, a country will on Monday mark the one-year anniversary of a mass shooting at a Quebec City mosque that killed six — an attack in which the suspect was reportedly a fan of French Front National leader Marine Le Pen’s xenophobic views.

These three criminal cases again raise the debate about how the spread of hateful or radical views can lead to violence, and whether those who espouse such rhetoric should be held responsible for actions taken by those who consume it.

If that debate — over how people become radicalized online or by public figures — sounds familiar, it’s because it is.

In the wake of the Sept. 11, 2001 attacks, a multimillion-dollar industry of counterterrorism research uncovered an army of dangerous propagandists, but this work focused almost exclusively on violent Islamic extremism that fuelled groups such as Al Qaeda or Daesh, also known as ISIS and ISIL.

Attention is now increasingly shifting to examine the impact of far-right preaching, from fringe but popular websites to the Twitter account of the sitting U.S. president.

“There is growing recognition of the role that the indirect and direct narrative impacts of these sorts of speakers can have,” said Barbara Perry, a professor at the University of Ontario Institute of Technology, in an interview this week. Despite the fact that Ottawa has warned about the “rise in hate-related incidents reported to police” and the “potential for extreme right-wing motivated violence to occur,” Perry is one of Canada’s few academics who specializes in violent right-wing extremism.

“We’ve contributed to the ease in which the far right has flown under the radar with the security narrative that we subscribe to — ‘Islam is the enemy, Islam is the enemy, Islam is the enemy,’” she said.

CNN host Don Lemon condemned President Trump’s vilification of the press on Tuesday after the arrest of Brandon Griesemer, the Michigan man charged with calling in repeated threats to the station’s Atlanta headquarters. In one call, he allegedly said: “I have more guns than you. More manpower. Your cast is about to get gunned down in a matter of hours.”

“There’s nothing random about this. Nothing,” Lemon said on air. “This is what happens when the president of the United States, Donald Trump, repeatedly attacks members of the press for simply reporting facts he does not like.”

Addressing Trump directly, he said: “People take that message seriously. And if one of us is hurt … it won’t be a fake injury or, sadly, a fake death.”

The same day, London prosecutors told a terrorism trial that accused Darren Osborne, 48, who is charged with killing 51-year-old Markham Ali and attempting to kill others as they left a Finsbury Park mosque in north London last June, had been brainwashed by online material.

According to British press reports, Osborne’s partner testified that he had become a “ticking time bomb” before the attack, fuelled by the words of Jayda Fransen, the deputy leader of the far-right Britain First party; mass emails sent by Tommy Robinson, the former leader of the anti-immigrant English Defence League and current host for conservative Canadian website Rebel Media; and conspiracy theory-peddling sites such as Infowars.

Two weeks before the attack, the court heard that Osborne had received a direct Twitter message from Fransen, although the content of the message was not revealed.

Trump ignited an international firestorm in November after he retweeted three of Fransen’s anti-Muslim videos.

Robinson this week protested being linked to the ongoing London trial, writing on Twitter: “You have put my life in danger today with your fake news & misrepresentation. Every newspaper in the uk has pushed these lies. I’m being directly linked & blamed for a terrorist attack that has absolutely nothing to do with me.”

Prosecutors allege Osborne kept screenshots of some of Robinson’s emails, including one promoting a march against the Manchester terrorist attack that killed 22 and injured more than 100 last May. “What Salman Abedi did is not the beginning, and it won’t be the end,” read the email. “There is a nation within a nation forming just beneath the surface of the UK. It is a nation built on hatred, on violence and on Islam.”

In an email to the Star, Rebel Media founder Ezra Levant dismissed any link between Robinson’s group emails and the London attack.

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“The e-mails referred to are generic e-mails we send to thousands of our viewers who sign up to our website. They are not personal e-mails,” Levant. “For example, we have 44 people with e-mail addresses at The Toronto Star who receive our e-mails, as well as many British journalists.”

“To equate that peaceful, multi-racial protest to the violent, terror attacks themselves is not only fake news, it trivializes terrorism. It falsely equates the suffering of actual victims of violence with mere political disagreement.”

Rebel Media lost several high-profile hosts and columnists in the wake of a contributor’s sympathetic coverage of white supremacist groups following deadly protests in Charlottesville, Va., last August.

Conservative leader Andrew Scheer later distanced himself from the website, writing in a statement: “I believe there is fine line between reporting the facts and giving those groups a platform … Until the editorial directions of the Rebel Media changes, I will not grant interviews to the outlet.”