A Russian fraud whistleblower could have been the victim of a "reprisal killing" in Britain linked to the deaths of Alexander Litvinenko and lawyer Sergei Magnitsky, an inquest has heard.
Alexander Perepilichny, 44, died after collapsing while running near his Surrey home in November 2012.
His death was originally attributed to natural causes but traces of a chemical that can be found in the poisonous plant gelsemium elegans were later found in his stomach.
His pre-inquest review today heard that before his death he was helping a company called Hermitage Capital Management - for whom Magnitsky had also worked - on uncovering a 230 million dollar (£150m) Russian money laundering operation.
At the hearing in Woking, Hermitage's lawyer Henrietta Hill QC claimed Perepilichny had been on an underworld "hit list" and had received death threats. There was a "clear parallel" between his death and that of Magnitsky, who died in prison in 2009, she said.
Ms Hill, making a successful application for the firm to receive "interested person" status in the inquest, said Perepilichny had brought them "explosive" evidence and had met representatives several times shortly before his death.
She said: "There is an objective basis for ruling that the deceased lost his life by virtue of a reprisal killing for helping Hermitage uncover this fraud. There is concern there is a pattern of reprisal killings. This deceased died in a manner that was inextricably linked to this work with Hermitage."
Sergei Magnitsky was jailed in 2008 for tax evasion. He died there the following year of untreated pancreatitis after testifying against police officials, accusing them of stealing 230 million dollars in tax rebates.
It has been claimed he was repeatedly beaten and denied medical treatment. Ms Hill added that Perepilichny, who had been living in Weybridge, Surrey, was also the subject of lawsuits brought by a company owned by Dmitry Kovtun, a suspect in the assassination of Mr Litvinenko in London in 2006.
French police are also investigating Perepilichny's death after it was found he visited Paris shortly before he died, the court heard.
Lawyers for Legal and General, with whom he took out a life insurance policy months before his death - it came into force days before he died - are also questioning the manner of his death. But his family's lawyer argued today that there is so far no evidence of foul play as further chemical tests have yet to confirm or disprove the presence of the poison.
Alexandra Tampakopoulos told senior Surrey coroner Richard Travers that Hermitage was "playing to the gallery" with an application based on "supposition".
She said that the firm was using "lazy stereotypes" and had no direct evidence he was murdered or had received threats - he had no security guards and was running alone when he collapsed.
She said: "There is no evidence of connection to Sergei Magnitsky's death, a death that occurred in wildly different circumstances in Russia, in custody, in 2009."
She added: "The suggestion of some link between Perepilichny and Dmitry Kovtun and the Litvinenko inquiry, I warn you not to fall into the trap that you are being invited to fall into."
She continued: "Indeed, evidence has been put forward by the family that supports death by natural causes."
The full inquest is due to take place in September and last five days.