- Over a week after a young scientist died under mysterious circumstances at a Siberian plague institute, the Kremlin has still not publicly identified the germ that killed her. Russia has not provided a formal answer to the question of how Darya Shipilova, a 28-year-old researcher at the Anti-Plague Institute of Siberia and the Far East, died on October 2. She was put into a hospital in Shelekhov, a town about 12 miles south-west of Irkutsk, on September 29, where she sadly died just a few days later. So far, the Kremlin has only said she died from 'pneumonia of unknown aetiology [origin]', without going into any more detail. The World Health Organisation said on Saturday that it still does not know how Darya died. Worse still, her family are now refusing to discuss her death publicly, amid fears they have been gagged. Last week, her mother shot down theories that Darya may have been infected after she broke a test tube containing bacteria. Medical professional Svetlana Shipilova claimed it is 'impossible' to break the test tubes used in these research institutions. She said: 'I don't want to read nasty things about my child. I know the truth. I find myself fending off foolish acquaintances who actually believed all that.' Now, Darya's father and brother have refused to speak, local media reported. Little is known about the young scientist's funeral plans either, as there was earlier speculation about whether she would need to be buried in a zinc coffin to prevent the spread of a dangerous infectious disease. Darya was involved in testing out antibiotics that fought the Y. pestis bacterium – which causes the plague – according to the New York Times. On Saturday, the WHO called for a continued investigation into the Siberia incident, adding that it is still seeking to understand the 'causative agent' of Darya's fatal pneumonia. Russian health officials, it said, had conducted more than 5,500 tests and found no evidence of any dangerous pathogenic