A Russian mafia whistle-blower who was found dead after going out for a run near his home in southern England six years ago probably died of natural causes rather than from an elaborate poison plot, a British coroner found on Wednesday.

Alexander Perepilichny, 44, was found collapsed and vomiting near his luxury home on the exclusive St. George's Hill estate in Weybridge, 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, his role in helping a Swiss investigation into a Russian money-laundering scheme, and the mysterious deaths of other Russian exiles in Britain sparked speculation that he might have been murdered.