SOFIA Bulgaria has decided to extend its investigation into the murder in 1978 of dissident Georgi Markov in London with a poison-tipped umbrella, a top investigator said on Wednesday.
Boyko Naidenov, head of the National Investigation Service (NIS), said the case would remain open even though the 30-year statute of limitations expires on Thursday.
"The investigation will continue ... I will assign additional investigators to the case who are not biased," he told Reuters. "It is extremely important to get to the truth".
Bulgarian media have reported that British politicians urged Sofia not to close the probe into the murder, one of the most notorious Cold War crimes.
Markov, a writer, journalist and opponent of Bulgaria's then communist regime, died on September 11, 1978 after a stranger shot a ricin-laced pellet into his leg on London's Waterloo Bridge.
Naidenov said the case was linked to an assassination attempt against dissident Vladimir Kostov, which meant that its statute of limitations was 35 rather than 30 years.
On Monday, Luchezar Penev, head of the NSI's Serious Crimes Investigation unit, told Reuters that the popular story that an umbrella was used to inject the poison had not been confirmed.
Naidenov said not many facts had been established on the case and pledged to request help from the intelligence service -- a successor to the foreign operation unit of the communist era secret police -- and full access to its archives.
According to accounts of the incident, Markov, who defected to the West in 1969, was waiting for a bus when he felt a sharp sting in his thigh. A stranger fumbled behind him with an umbrella he had dropped and mumbled "sorry" before walking away.
Markov died four days later of what is believed to be ricin poisoning, for which there is no antidote.
British police remain eager to solve the murder.
Naidenov said Sofia had assured London that the Balkan country, once Moscow's most obedient satellite, would keep the probe open and cooperate with the British police.
On Monday, Bulgarian daily Dnevnik published an investigation into communist-era secret police files which identified Markov's suspected assassin as agent code-named "Piccadilly."
The files show how the agent underwent "special training" from Bulgaria's notorious secret police, Darzhavna Sigurnost, and received two medals, several free holidays and $30,000 after Markov's death, Dnevnik said.
The files, which Dnevnik said were incomplete, unveiled that Markov's case was discussed with the KGB in Moscow.
(Reporting by Tsvetelia Ilieva; editing by Keith Weir)