He went down with a single punch. Arkadiusz Jozwik, shy, devoted to his mother and an immigrant to Britain from his native Poland, was out with friends late last month enjoying pizza and drinks when they were set upon by a group of teens, some reportedly shouting anti-Polish slurs.

The punch knocked Jozwik to the ground, the back of his head slapping the concrete of the rundown pedestrian plaza in the hardscrabble London suburb of Harlow. The 40-year-old was taken off life support days later.

Now Jozwik’s violent death is reverberating throughout Britain, and across Europe, as the latest evidence of a post-Brexit surge in suspected hate crimes directed at immigrants.

When anti-immigrant assaults first started rising after the June 23 vote to leave the European Union, authorities expressed hope that the spike would prove temporary.

But nearly three months later, the rate of such crimes remains sharply higher than it was last year, generating fears that the xenophobic passions unleashed by the Brexit vote have created a new normal of fear and intimidation for the country’s approximately 8.5 million foreign-born residents.

It may get worse: those who backed Brexit, expecting the vote to leave the EU would yield mass deportations and a ban on new immigrant arrivals, are bound to be disappointed by the years-long bureaucratic slog that lies ahead, which could lead to even more violence as frustration sets in.

Eric Hind, a Polish-born friend of Jozwik’s, said the day after the vote that he received messages on Facebook: “What time is the next bus back to Poland?” His mother and his sister were told by their factory manager that “now you Poles need to pack up your bags and go back home”.

The vote mandated no such thing. But the threat of violence may force them out just the same.

“People are scared and horrified,” Hind said. “I’m scared and horrified. My wife wants to move back to Poland. I keep saying, ‘Let’s not panic.’ Arek’s death was one case. But it could have been me.”

Such is the depth of concern that the Polish national police sent two officers to Harlow last week to patrol the town, which was largely built in the 1950s as a concrete-clad socialist utopia for London residents who were bombed out during the Blitz.

In more recent decades, Harlow has struggled with closed factories and wide income disparities, even as immigrants have moved in to launch businesses and get a foothold in their new land.

“A lot of people here feel like they’ve been left behind,” said Owen Jones, senior organiser for the anti-extremism group Hope Not Hate.

“Britain’s moving on at a huge pace, but their situation is getting worse and worse. Then they see immigrants driving around in nicer cars and living better lives than they do. It creates even more resentment.”

In the pedestrian plaza where Jozwik died — its storefronts dominated by liquor shops, betting parlours and faded bars — officers with “Policja” stamped on their blue uniforms are walking the beat alongside those bearing the more familiar bulbous black caps of a British bobby.

The Polish officers have no formal police powers in Britain. But their highly unusual assignment was intended to help to “engage with members of the Polish community who do not speak English as their first language”, according to the local Essex police force.

The arrival of the officers followed days after a visit to London by Witold Waszczykowski, the Polish Foreign Minister, who cited Jozwik’s death and other attacks in arguing that the Brexit vote had spawned an eruption of violence against immigrants who “deserve to be respected and secured”.

Last week, European Commission president Jean-Claude Juncker used his annual state-of-the-EU address to speak out about Jozwik’s killing and the rising British nativism that it has come to represent.

“We Europeans can never accept Polish workers being harassed, beaten up or even murdered on the streets of Essex,” Juncker said.

British leaders, too, have strongly condemned the rise in hate crimes. Theresa May, the Prime Minister, has addressed the issue from the floor of the House of Commons and phoned her Polish counterpart to express her “deep regret” at crimes such as the attack on Jozwik.

In Harlow, his death has spawned a reckoning over the town’s problems with anti-immigrant prejudice.

“This isn’t a town where everyone has pitchforks and is outright racist,” said Emma Toal, deputy leader of the Harlow Council. “There’s a big portion of the community that is shocked by this and doesn’t want any Polish person to have to fear violence.”

But Toal acknowledged there were some in Harlow who are hostile towards immigrants, and who had been deceived by pro-Brexit politicians into thinking that a vote to leave would force foreigners to head home.

“People thought they were voting to take back control, and that many immigrants wouldn’t be allowed to stay,” she said.

Those with such views may be a minority in Harlow. But they are not difficult to find.

The tree-shaded spot where Jozwik was attacked is now strewn with flowers, candles, Polish football jerseys and messages of peace. “Down with racism!” reads a hand-lettered sign in black ink.

A man with a buzz cut walking past the site, his pitbull tugging at the end of a short leash, explained to a young child one recent day that the tribute was “a memorial for something that happened to scum”.

Others here vehemently deny that the town has a problem with prejudice, and say Jozwik was killed not because he was a foreigner but because he was unlucky — chosen randomly by teens looking for trouble.

“It had nothing to do with racism, but it’s become politicised,” said Sue Keningale, a local resident who puffed on an electronic cigarette as she waited outside a laundromat. “Yeah, it was a Polish guy who died. But what would have happened if it was an English guy?”

Keningale said the real problem in Harlow is that young people have nothing to do, and police do little to disrupt violent behaviour. “There’s been trouble here before with the kids,” she said. “It’s not a new thing.”

Hind said he does not believe the attack was random. He said he had spoken with another friend who survived the assault by the teens who told him that “the whole atmosphere changed when they said they were Polish”.

Hind said of the death of the burly factory worker: “It was a hate crime. It’s because of where he came from.”

Police have confirmed they are investigating that possibility.

Hind, an information technology manager who organised a peace vigil in his friend’s honour, said he worries that for all their rhetoric, authorities are not taking the rise in hate crimes seriously. He described the presence of the Polish officers as “a joke” and said it would do nothing substantive to address immigrants’ concerns for their safety.

That makes him nervous, even as he resists his wife’s pleas to move the family away from the hostility they feel in Harlow and back to their homeland.

“I’m not going to let this destroy everything I’ve worked for,” Hind said. “I came here to achieve something.”

Griff Witte is The Washington Post’s London bureau chief. He previously served as the paper’s deputy foreign editor and as the bureau chief in Kabul, Islamabad and Jerusalem. Karla Adam contributed to this report