LONDON (Reuters) - A British judge investigating the sudden death of a Russian mafia whistleblower heard on Monday that he might have been murdered by eating poisoned soup.

Alexander Perepilichny, 44, was found dead near his luxury home on the exclusive gated St George’s Hill estate in Weybridge, Surrey, southwest of London, after he had been out jogging in November 2012.

The sudden nature of the death of Perepilichny, who had sought refuge in Britain in 2009, and his role in helping a Swiss investigation into a Russian money-laundering scheme has sparked speculation that he might have been murdered.

Surrey Police have said there was no evidence for this but an earlier pre-inquest hearing was told traces of a rare and deadly poison from the gelsemium plant had been found in his stomach.

The case has drawn parallels with the murder of ex-KGB agent and Kremlin critic Alexander Litvinenko who died after his tea was poisoned with a rare radioactive isotope in London in 2006.

A public inquiry into his death last year concluded that Russian President Vladimir Putin had probably given the go-ahead to a Russian intelligence operation to murder Litvinenko, a claim that Moscow rejected.

Perepilichny had been providing evidence against those linked to the death of lawyer Sergei Magnitsky while in custody in Moscow in 2009. Magnitsky had accused Russian government officials of stealing $230 million.

“Either he died of natural causes or he was murdered,” said Bob Moxon Browne, the lawyer for Legal & General, with whom Perepilichny had taken out a large life insurance policy.

“If he was murdered, it does seem very likely he was poisoned,” he told Monday’s pre-inquest hearing at London’s Old Bailey court.

He told the court there were telephone records of threats from an organized crime group and that police had flushed away the contents of Perepilichny’s stomach. He also queried why his widow had never given a witness statement about what Perepilichny had had for lunch on the day he died.

WAS HIS SOUP POISONED?

Moxon Browne said there was hearsay evidence that Perepilichny had enjoyed a large bowl of soup containing sorrel, a popular Russian dish, and suggested the vegetable could have been swapped.

“A minute quantity of material that was subsequently recovered from the stomach cavity ... has revealed a compound which has an atomic weight to four decimal places which corresponds to a poison,” he said.

Fiona Barton, the lawyer for Surrey Police, said numerous samples had been taken from Perepilichny’s body and subjected to comprehensive analysis

“No identifiable toxin was found and that remains the case,” she said.

Last November, the government successfully applied to London’s High Court for “public interest immunity” (PII) over secret material it held regarding the Perepilichny case, meaning it could not be made public at an inquest on national security grounds.

Following that decision, the original coroner was replaced with senior judge, Nicholas Hilliard, and his preliminary view was that the PII documents were not significant.

“Nothing in the material ... materially assists the question of how Alexander Perepilichny died,” said Peter Skelton, the lawyer to the inquest.

Henrietta Hill, lawyer for Hermitage Capital Management which employed Magnitsky, said Hilliard needed to answer the “Litvinenko” question of whether the inquest, due to start on June 5, would have to be abandoned because it could not examine secret documents, and be replaced by a public inquiry instead.

“The material to which PII attaches is the government answer to specific questions about threats to Mr Perepilichny’s life, third party involvement in the death and his contact with certain individuals,” Hill said.