The shooter left a trail of evidence for police to track: a distinctive backpack abandoned in Central Park; a water bottle with DNA found at the crime scene; and a collage of surveillance video of him throughout the city, including a photo of him with his mask down at the hostel.

But the clue that has ignited the most chatter online, and that appears to have garnered the gunman a following, are the words officials say they found scribbled in permanent marker on bullet casings discovered at the scene: “depose”, “deny” and “delay”. Although the words could have multiple meanings, they may be a reference to the tactics used by insurers of all kinds to avoid paying claims.

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In some circles, those words alone have been enough for people to openly root for the shooter and hope that he escapes the grasp of law enforcement.

Alex Goldenberg, a senior adviser at the Network Contagion Research Institute, which tracks online threats, said the internet rhetoric had left experts “pretty disturbed” by the glorification of the murder of Brian Thompson and the “lionisation of the shooter”.

In a report this week, the institute found that of the top 10 most-engaged posts on the social platform X about the shooting on Wednesday, six “either expressed explicit or implicit support for the killing or denigrated the victim”. The dynamic is similar to the discourse that often emerges after a mass shooting on websites such as 4chan and 8chan, where perpetrators of extreme violence become memes themselves, Goldenberg said, “but what’s disturbing about this is it’s mainstream”.

“It’s being framed as some opening blow in a broader class war, which is very concerning as it heightens the threat environment for similar actors to engage in similar acts of violence,” Goldenberg said.

On Saturday afternoon, about half a dozen men gathered in the December cold at Washington Square Park in Lower Manhattan to participate in a lookalike contest for the gunman. One had the words “deny, defend, depose” painted on his jacket.

The contest drew a crowd of about 30 people who had heard about the event through flyers advertised on social media platforms, including X and Bluesky.

The winner, a 39-year-old who does data entry for a labour union, declined to give his name but said that he celebrated the gunman’s actions and that he believed it was important to make people understand how people were hurting under the healthcare system.

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For executives of large corporations, particularly those in the pharmaceutical and insurance industries, Thompson’s killing heightened their safety concerns. Hours after the shooting, dozens of private security officers joined a call to discuss additional protective measures for executives.

But for others, the message that the internet has assigned to the shooter’s motives has resonated and spread.

More than 160 kilometres away from Manhattan, in a Philadelphia alleyway next to a graffitied dumpster, the words “deny”, “defend” and “depose” were spray-painted on the side of a building.

This article originally appeared in The New York Times.

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