A murder investigation was launched today following the death of a British woman after being exposed to a "high dose" of a deadly nerve agent close to a city where a former Russian spy and his daughter were poisoned with the same chemical four months ago.
Dawn Sturgess, 44, died at Salisbury District Hospital in Wiltshire yesterday after falling ill on June 30.
Her partner Charlie Rowley, 45, who also fell ill after being exposed to the nerve agent, remains in a critical condition in hospital.
Scotland Yard said they have launched a murder investigation - the second major probe involving the military-grade nerve agent this year, following the case of Sergei Skripal and his daughter in March.
Tests have revealed that the Amesbury couple were exposed to Novichok, a nerve agent developed by the Soviet military during the Cold War in what is the first known offensive use of such a chemical weapon on European soil since World War II.
Security services believe the couple were inadvertently exposed to the same nerve agent used to attack Skripal and his daughter four months ago.
Assistant Commissioner Neil Basu, head of UK counter-terrorism policing, which is leading the investigation, said he was "unable to say" if the incident in Amesbury is linked to the poisoning of the Skripals on March 3 - but it is their "main line of inquiry".
The Indian-origin officer said: "In the four months since the Skripals and (Detective Sergeant) Nick Bailey were poisoned, no other people besides Dawn and Charlie have presented with symptoms, but their reaction was so severe it resulted in Dawn's death and Charlie being critically ill.
"This means they must have got a high dose and our hypothesis is that they must have handled a container that we are now seeking," he said.
"This terrible news has only served to strengthen our resolve to identify and bring to justice the person or persons responsible for what I can only describe as an outrageous, reckless and barbaric act," he said.
"Police and security officials are working urgently to establish the facts of this incident, which is now being investigated as a murder. The government is committed to providing full support to the local community as it deals with this tragedy," she said.
The UK home secretary Sajid Javid had demanded an explanation from Russian authorities last week over how the deadly Soviet era poison ended up poisoning former Russian spy Sergei Skripal and his daughter Yulia in March and then the British couple more recently.
However, Russian authorities have repeatedly denied any involvement.
After the hospitalisation of Sturgess and Rowley, Javid accused the Russian state of using Britain as a "dumping ground for poison".
The Russian Embassy hit back, accusing the government of trying to "muddy the waters" and "frighten its own citizens".
In a statement, the Met Police has said that the possibility the poisoning of the Skripals and Sturgess and Rowley are linked is a "clear line of inquiry".
Following the death, there are growing fears of a wider risk to public health in the region but Public Health England stressed the risk to the general public "remains low".
Professor Paul Cosford said: "As a precaution we still advise the public not to pick up any strange items such as needles, syringes or unusual containers."
"Wash your clothes in a washing machine and to keep your items double-bagged and securely fastened, if they are dry-clean only," he said.
(This story has not been edited by Business Standard staff and is auto-generated from a syndicated feed.)