When Leonid Volkov, a longtime associate of the late Russian opposition leader Alexei Navalny, was brutally attacked with a hammer outside his home in Lithuania in March, it initially seemed yet another case of the Kremlin hunting down its enemies abroad. The assailant smashed open Volkov’s car window and struck him repeatedly with a hammer, breaking his left arm and damaging his left leg. Western officials and opposition figures assumed the attack, which took place a few weeks after Navalny’s mysterious death in prison, had been orchestrated by the Kremlin. Then, last month, Navalny’s team released an explosive investigation that cast doubt on that version of events. In the video, Maria Pevchikh, the head of Navalny’s investigation department, accused the wealthy businessman and outspoken Kremlin critic Leonid Nevzlin of hiring the men to beat up Volkov outside his home, claiming the attack was triggered by a personal dispute. Nevzlin has denied any involvement in the attack. In a statement on X, he wrote: “I have nothing to do with any attacks on people, in any form whatsoever,” adding that “justice will confirm the absurdity and complete baselessness of the accusations against me”. In their investigation, Navalny’s team published screenshots they said showed conversations on the messaging app Signal between Nevzlin and an alleged associate, Anatoly Blinov, apparently discussing the attack on Volkov. Navalny’s team handed their dossier of evidence to Polish authorities, where Blinov was arrested in September. The allegations have caused shock and led to infighting among members of the exiled Russian opposition, as people come to terms with the implications of the revelations, if true. Pevchikh, of Navalny’s Anti-Corruption Foundation, told the Guardian: “There isn’t a rulebook on what you do when you find out that someone you know stabs you in the back. “Volkov was attacked three weeks after Alexei was killed. We had barely buried him. In the lowest point of our lives, someone pushes you from behind so you fall even more and suffer even more.” Nevzlin, a former executive and partner of the ex-oil tycoon Mikhail Khodorkovsky, gave up his Russian citizenship after the start of Moscow’s full-scale invasion of Ukraine and is now based in Israel, where he owns a stake in the Haaretz newspaper. From Israel, Nevzlin has funded several media projects that are critical of the Kremlin and voiced staunch support for Ukraine in its war with Russia. He has previously clashed with other opposition groups, including Navalny’s team, over disagreements regarding the best approach to challenge Vladimir Putin, the Russian president. Nevzlin is known for his more radical political views, including calling for the dissolution of Russia as a country and referring to the majority of Russia’s population as “slave cattle”. The Navalny team’s investigation is based partly on a cache of private Signal screenshots they have obtained, which, they say, reveal exchanges between Nevzlin and a fixer, allegedly Blinov, a Russian lawyer. Pevchikh stated in the video investigation that the screenshots were provided by a middleman with ties to Russia’s FSB security service. The Guardian was unable to verify the authenticity of the conversations, which also featured covertly shot photos of Volkov and other members of Navalny’s team living in Vilnius. “Time to do away with this moron,” reads one of the messages, which the Navalny team claims Nevzlin wrote. They further allege that Nevzlin, in the messages, discusses plans to abduct Volkov in a way that would leave him “in a wheelchair” before handing him over to the FSB. The Navalny team said in a statement it believed “stupid senseless hatred” combined with “political competition” may have driven the attack on Volkov. The Polish law enforcement agency said Blinov was under investigation on three charges, “including the charge of orchestrating the assault on Russian opposition activist Leonid V due to his political identity and activities”. So far, they have not made any comment on the allegation that Nevzlin was behind the attack. “Many different scenarios have to be investigated. We also know that in such cases, disinformation is often being shared,” said Stanisław Żaryn, a national security adviser to the Polish president, in an interview in Warsaw. The arrest of Blinov came months after Polish authorities detained two men suspected of attacking Volkov, based on a European arrest warrant issued by Lithuania. Prosecutors said they were investigating eight people in the case – six Poles, a Belarusian and the Russian who has been charged. The Polish prosecutor’s office said it was looking at events “that took place both in Europe (including Vilnius) and in South and North America”. It was not immediately clear what incident authorities were referring to, though Pevchikh in the investigation also claimed Nevzlin was behind an attack on the wife of a well-known Russian economist based in Argentina who has feuded with Nevzlin on social media. Nevzlin in turn told Sota, an opposition media outlet he sponsors, that Blinov, the fixer, was seeking to implicate him in ordering the attack on Volkov, and denied involvement in organising any attack. He said he himself filed a report to the Lithuanian police on 5 August about what he described as a provocation. The community of Russian dissidents living abroad has long been disposed to infighting, but the accusations against Nevzlin have provoked the biggest split in the opposition movement since the start of Russia’s full-scale invasion of Ukraine in February 2022. Navalny’s team has also accused Khodorkovsky, once Russia’s richest man who spent 10 years in prison after falling out with Putin, of being aware of Nevzlin’s alleged crimes before they became public. Khodorkovsky has defended his former business partner Nevzlin, claiming the screenshots were probably part of a scheme orchestrated by Russian security services. “Either it is true, and Leonid Nevzlin has gone mad, or it is an FSB provocation and a fake on which a lot of money has been spent … For perfectly understandable reasons, I lean towards the second,” Khodorkovsky said last month. Khodorkovsky flew into Warsaw on Monday and met Polish prosecutors to share his own information about the case. In an interview on Wednesday, Khodorkovsky said he still believed the evidence was probably faked by Russian authorities. He also suggested the most implausible part of the allegations was not that Nevzlin could have theoretically ordered the attack, but that he would have been clumsy enough to leave a trail of evidence. “There are things you can believe in, although it would be idiotic and hard to see why. But then there are things that it is absolutely impossible to believe,” he said. The scandal risks further splitting Russia’s already marginalised opposition, which has been scattered across European capitals since Moscow’s invasion of Ukraine in 2022 and Putin’s brutal crackdown on dissent. Without Navalny, regarded as a unifying figure and Putin’s most formidable opponent, the opposition finds itself lacking a clear leader. The public quarrels have been eagerly picked up by Russian state media propagandists, who have been leveraging the scandal to further discredit the opposition. Pevchikh said: “It is damaging to all the sides including us, and it’s probably a life-changing event in terms of the Russian opposition … But in these very difficult situations you just have to speak the truth, however sad and scary it is.”