The fatal attack on a pro-European British lawmaker just a week ahead of the key Brexit referendum vote has shaken politicians and voters across the U.K.
While this is the first time in nearly a quarter of a century that a U.K. politician has been murdered, the case bears startling similarities to the assassination 13 years ago in Sweden of pro-EU Anna Lindh.
Days before Sweden would vote on whether to join the euro in 2003, a 46-year-old lead campaigner for Sweden's to adopt the euro was stabbed while shopping in a Stockholm department store. She had been shopping for clothes for a euro zone debate scheduled that evening. The next day, on September 11, Social Democratic foreign minister Lindh died from her injuries.
Both sides of the Swedish political campaign suspended their activities following the news, with TV ads campaigns cancelled and billboard and print media ads withdrawn.
On the following Sunday, Swedes rejected proposals to adopt the common currency.
Back in Britain, the death of Labour member of parliament (MP) Jo Cox has set a similarly solemn tone around the otherwise raucous Brexit debate.
The 41-year-old was shot in the small town of Birstall in the north of England while on her way to meet with constituents in a nearby library Thursday afternoon.
According to reports of unconfirmed eyewitness accounts, the attacker shouted 'Britain first,' potentially referencing a right-wing, anti-immigration and eurosceptic group in the U.K.. It has led to speculation that the politician's murder may be linked to the upcoming June 23rd referendum.
Media reports have identified the suspect as a 52-year-old local man Tommy Mair, who is said to have lived alone in a nearby estate.
A full investigation is underway by authorities to determine the motives of the suspect, who is believed to have acted alone.
Though it's unclear whether there was any political intent behind Cox's murder, both sides of the EU referendum have since suspended campaign activities.
The political pull-back is in stark contrast to a debate that was otherwise reaching fever pitch less than a week before Brits headed to the polls.
Just on Wednesday, Cox's husband and children were on a boat on the River Thames in support of the 'Remain' camp, as Brexit supporters took to their own flotilla. Both sides trading insults over loud speakers and in one of the stranger moments, protesting fishermen deployed water hoses.
Since news of the attack, the tone has darkened.
On Thursday night, Bank of England Governor Mark Carney, who has been criticized for making comments on the economic risks of the upcoming referendum, changed direction in a speech to London City bankers, taking the opportunity to pay tribute to the slain politician.
Meanwhile, the International Monetary Fund, which has warned about the consequences of leaving the EU, delayed the release of a report on the impacts of a Brexit.
In the wake of the suspended campaigns, markets rebounded, sending sterling and the U.K.'s FTSE 100 higher. There are suspicions that the attack on the pro-EU politician may temper the momentum of the pro-Brexit camp and reduce the prospects that voters will want to leave the European Union.
However, while the attack on Sweden's minister in 2003 didn't beckon voters towards closer ties to the EU, voters notably opted for the status quo.
"It is difficult to know whether or not a specific incident such as this will have a decisive impact on the overall result of the referendum," Matthew Goodwin, a politics professor at the University of Kent and senior visiting fellow at Chatham House told CNBC via email.
"We currently know little about the event, individual and his potentially political motivations," Goodwin stressed.
In Sweden, it took nearly a decade for the motivations of the attack to reach the public.
Mijailo Mijailovic would break his silence eight years later, telling Swedish tabloid Expressen that he hadn't planned to target Lindh in particular, but took his hatred of politicians out on the minister after spotting her in the store while high on the hypnotic drug Flunitrazepam.
The 32-year-old Serbian-Swede also admitted that he made up claims that he'd heard voices in an effort to escape a normal prison sentence.
Mijailovic was sentenced to life in prison.