String of mystery spy deaths in UK
SPIES killed under mysterious circumstances include Russian Alexander Litvinenko, whose death sparked global interest.
The 43-year-old was poisoned in London in November 2006 by radioactive polonium-210.
Litvinenko had fled to Britain where he became a critic of the Kremlin. Vladimir Putin was thought to have approved his assassination.
Businessman Alexander Perepilichny was allegedly killed near the capital in 2012 as part of a conspiracy to cover up the theft of £166million from the Russian Treasury. There was no trace of poison in the autopsy but his insurers claimed their checks found some in his stomach.
The death of Georgi Markov – the Bulgarian dissident poisoned by the tip of an umbrella in London – remains one of the Cold War’s great unsolved mysteries.
He was assassinated on the orders of the Bulgarian secret service in September 1978.
The weapon that killed him was partly developed by the Soviet KGB.