An investigation into the murder of a Bulgarian defector in London with a poisoned umbrella has been closed, Bulgaria's chief prosecutor says.
He says that 35 years after one of the most notorious killings of the Cold War, the case has reached the statute of limitations.
Georgi Markov, a journalist and government critic who fled Bulgaria and settled in the UK, was jabbed in the thigh with an umbrella tip on Sepember 7, 1978 as he waited for a bus at London's Waterloo Bridge. He had been injected with the poison ricin and developed a fever, dying four days later.
Suspicion fell on the Bulgarian secret police, but no one has been arrested or charged in the case. Prosecutor Sotir Tsatsarov said on Thursday that his office was ready to provide legal assistance to British authorities. There is no statute of limitations on murder in the UK.
The decision to close the case drew outrage from critics who say post-communist authorities have dragged their feet on evidence the KGB and Bulgarian secret police were involved.
Markov was a harsh critic of his country's communist regime in reports for the BBC and Radio Free Europe when he was killed. British government scientists later discovered the umbrella had been used to inject a pinhead-sized pellet of the poison ricin into Markov's leg. The fatal pellet is one of the artefacts in a macabre crime museum - closed to the public - inside Scotland Yard headquarters, alongside letters from Jack the Ripper and other grim mementoes.
Bulgaria was the most loyal Soviet ally under decades of Communist rule. Post-Communist leaders had vowed to clear the Markov case in an effort to clean up Bulgaria's image, but as with trials of former communist leaders, police officers and labor camp guards, the results have been patchy.
In closing the case, "Bulgaria and its prosecution are admitting to being either powerless or lacking the will to reveal one of the most horrific crimes of the communist regime - murder over speech, not action," prominent columnist Petya Vladimirova wrote on Thursday. Suspicions that Bulgarians were involved in the killing grew after Oleg Kalugin, a former KGB agent, said in 1992 that Bulgaria asked Moscow for help in the assassination.
The next year, Danish authorities charged a Dane of Italian origin, Francesco Guillino, with killing Markov. Guillino, who reportedly had worked for the Bulgarian secret services since 1972, denied wrongdoing and eventually was freed while Danish police awaited further evidence from Bulgaria that never came. A Bulgarian journalist claimed in 2005 that he had found evidence confirming the killing was plotted and carried out by Bulgaria's former communist secret services and that Bulgaria's post-communist authorities had covered up the case.
London's Metropolitan Police said its investigation remains open. The force said the case is "a particularly complex investigation, and we continue to work with the appropriate international authorities to investigate any new information that is passed or made available to police".