Markov remembered feeling a stinging pain from where he had been hit by the umbrella tip, and when he arrived at work at the BBC World Service offices he noticed a small red pimple had formed and the pain from being jabbed had not gone away. By the evening he fell ill, and died three days later.
After his death, doctors found a small platinum pellet, some 1.5mm across, embedded in his calf. Further examination found that it had two small holes drilled in it, which contained traces of the poison ricin.
Markov had worked as a broadcaster and journalist for the BBC World Service since his defection from Bulgaria, then a communist republic under the leadership of President Todor Zhivkov. He had criticised the regime many times on radio, and it is speculated that as a result of this, the Bulgarian government had asked the KGB to assist them in disposing of him.
Several high profile KGB defectors, such as Oleg Gordievsky have confirmed that the KGB was behind the assassination, but to this day no-one has been charged with Markov's murder.