A Russian businessman helping Swiss prosecutors uncover a powerful fraud syndicate has died in unexplained circumstances near his mansion in Britain.
Alexander Perepilichny, 44, sought refuge in Britain three years ago and was reportedly helping an investigation into a Russian money-laundering scheme by providing evidence against corrupt officials.
He also provided evidence against those linked to the death of Sergei Magnitsky, an anti-corruption lawyer in 2009.
Perepilichny is now the fourth person linked to the Magnitsky case to have died in strange circumstances.
His death occurred in Surrey on 10 November. His body, clad in running gear, was at the top of a hill.
The first report of the death first appeared on Wednesday in a report in the Independent newspaper, which is backed by Alexander Lebedev, a Russian billionaire who has spoken out publicly against the Kremlin.
The paper said Perepilichny was also a witness against the Klyuyev Group, a network of officials and underworld figures implicated in tax fraud who used European bank accounts to buy luxury property in Dubai and Montenegro.
In April, a former Russian banker was shot near London's Canary Wharf financial district. In 2006, former Russian spy Alexander Litvinenko died after drinking tea poisoned with polonium-210.