It was another mysterious Russian death on British soil.
One afternoon in November 2012, the businessman Alexander Perepilichnyy went out for a jog and never came back.
He was later found dead outside his mansion in Surrey.
Mr Perepilichnyy was about to give evidence in a huge fraud case linked to Russian organised crime.
Nearly six years on, as the inquest into his death is set to draw to a close, this programme has now learned that the government will be able to keep some key details secret – including whether the businessman ever had links to the British security services.
Jim Reed has the background to this extraordinary case.