Tests have confirmed that it was the same type of Novichok used to poison the Skripals, he said, and that Rowley and Sturgess "touched a contaminated item with their hands". Five hours after her collapse, police said, an ambulance was called back to the same address for Rowley, who also fell ill and was taken to hospital.
Rowley, 45, remains critically ill in hospital.
The British woman who was recently exposed to the same nerve agent that nearly killed a Russian spy and his daughter earlier this year has died, police said Sunday.
He said the murder investigation was being led by around 100 counter-terror detectives.
Basu said that Sturgess leaves behind three children, and offered thoughts and prayers for the woman's family.
Britain blames Russian Federation for the attack on the Skripals, an allegation Moscow has repeatedly denied. British government officials made a decision to boycott the games after the Skripal poisonings.
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Russian President Vladimir Putin's government has strenuously denied any involvement in either case, floating an array of theories about what might have happened and nominating an assortment of possible culprits.
A similar call was later issued by the Russian Foreign Ministry, which urged the United Kingdom to stop producing "the same old mantra "Russians did it" and get to the real investigation instead.
Prime Minister Theresa May said on July 8 that she was "appalled and shocked" by the death of Sturgess, and a spokesman for May said that Britain's interior minister will chair a meeting of the government's emergency committee on July 9.
It was the Kremlin's first reaction to the poisoning of two British citizens exposed to Novichok near Salisbury in England, where former Russian double agent Sergei Skripal and his daughter were poisoned in March.
She added: "The staff here at Salisbury District Hospital worked tirelessly to save Dawn".
Britain's public health authority acknowledged on Friday the concerns of people living in the area after the two incidents involving Novichok, but said it was confident that the risk to the public remained low.
Public Health England, which oversees public health and epidemiological surveillance, said the risk to the general public "remains low", but advised against picking up odd items like needles, syringes, and unusual containers.
Dmitry Peskov told reporters that Moscow "is deeply concerned" over the poisoning cases in Britain.