A Russian whistleblower could have been poisoned with soup but vital evidence about his last meal was "flushed away", an inquest has been told.
Alexander Perepilichnyy collapsed outside his Weybridge home in 2012. Traces of a chemical linked to plant poison were found in his stomach.
Claims have been made he was killed for helping to uncover a major fraud.
The pre-inquest hearing at the Old Bailey heard an ingredient in his sorrel soup may have been switched.
The latest pre-inquest review heard Mr Perepilichnyy had eaten a popular Russian dish based on the sorrel herb but tests had not indentified the herb in his stomach contents.Image copyright Reuters Image caption Mr Perepilichnyy collapsed outside his Weybridge home in 2012
Bob Moxone-Browne for Legal and General, which had issued a substantial life insurance policy to Mr Perepilichnyy shortly before his death, asked why no-one had asked his widow what he had had for lunch on the day he died.
He said: "The contents of Mr Perepilichnyy's stomach were flushed away very shortly after his death. There is a quantity of material that was subsequently retrieved from the stomach cavity."
The Russian was originally thought to have died of natural causes, but traces of a chemical that can be found in the poisonous plant Gelsemium elegans were later found in his stomach.
Mr Moxone-Brown told the hearing there was a "possibility somebody had substituted another vegetable matter for sorrel".
Hermitage Capital Management has claimed Mr Perepilichnyy may have been killed for helping it uncover a $230 million (£150 million) Russian money-laundering operation.
Henrietta Hill, for Hermitage, told the hearing: "There is an issue why Mr Perepilichnyy had so much life insurance. It has been suggested at one point he was advised to take out multiple policies by his bank manager."
Both Hermitage and Legal and General have argued Mr Perepilichnyy may have been murdered, possibly by agents of the Russian State.
There have been a number of pre-inquest reviews with one hearing being told Mr Perepilichny's death had parallels with the murder of former Russian spy Alexander Litvinenko.
The full inquest into Mr Perepilichnyy's death is due to start on 5 June.Image copyright Getty Images Image caption Mr Perepilichnyy's death has been compared to that of Alexander Litvinenko