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British detectives investigating the poisoning of two people with a military-grade nerve agent said Friday that a small bottle found in the house of one of the victims tested positive for Novichok, a lethal substance produced in the Soviet Union during Cold War.
Dawn Sturgess, 44, and Charlie Rowley, 45, fell ill on June 30 in a town in southwestern England near Salisbury, where British authorities say a former Russian spy and his daughter were poisoned with Novichok in March.
Sturgess died in a hospital on Sunday. Rowley was in critical condition for more than a week, but regained consciousness.
The Metropolitan Police said they found the bottle during searches at Rowley's house on Wednesday and scientists confirmed that the substance in the bottle was Novichok. The police interviewed Rowley since he became aware.
Police are still investigating where the bottle came from and how he entered Rowley's house. They said more tests would be done to try to establish whether the nerve agent was from the same lot that was used to poison former Russian spy Sergei Skripal and his daughter, Yulia.
More than 100 police officers had been searching for the source of the Rowley and Sturgess exhibition in the town of Amesbury, where they lived, and Salisbury, where the Skripals were poisoned.
The Skripals survived and were released from the Salisbury hospital before Rowley and Sturgess were poisoned and taken there. The British authorities took the father and the daughter to a protected secret place.
British police said earlier that they suspected the new victims had tampered with a container contaminated with Novichok and had no reason to believe that Rowley and Sturgess were deliberately attacked.
Commissioner Neil Basu, Britain's top anti-terrorist officer, told local residents this week that Novichok could remain active for 50 years if kept in a sealed container. He said he could not guarantee that there were no more traces of the deadly poison in the area.
Basu said Friday that the laces would remain in place in some places to protect the public despite the apparent progress in the case. He did not provide more information about the bottle found in Rowley's house.
"This is clearly a significant and positive development, however, we can not guarantee that there is no substance remaining," Basu said. The continuous blockade of areas would allow "continuing exhaustive searches as a precautionary measure for public safety and to help the research team."
The British Foreign Ministry said on Friday that the United Kingdom had asked the Organization for the Prohibition of Chemical Weapons to collect samples for analysis in its laboratories. The organization has the power to blame the use of chemical weapons.
The Novichok saga began in March when the Skripals mysteriously fell ill on a park bench in Salisbury. It was discovered that they had been poisoned with Novichok.
Prime Minister Theresa May blamed the Russian government for the attack, which the Kremlin has vehemently denied. The case led the United States and other countries to expel a large number of Russian diplomats.
Public health officials said that the risk of exposure to the public is low, but they advised people not to pick up any strange items.