The United Kingdom has opened a murder investigation into the death of a woman who was exposed to the Russian nerve agent Novichok.

Dawn Sturgess, 44, died Sunday night in a hospital after being exposed to the nerve agent on June 30 in Amesbury. Charlie Rowley, 45 was also exposed and is fighting for his life in the hospital.

The U.K. pointed fingers at Russia in March when former Russian spy Sergei Skripal and his daughter Yulia were poisoned with the same chemical close to where Sturgess and Rowley later came in contact with the nerve agent.

“There can be no doubt what was used and there remains no alternative explanation about who was responsible — only Russia has the means, motive and record,” then-British foreign-affairs secretary Boris Johnson said about the Skripals’ poisoning in an April statement.

Kremlin spokesman Dmitry Peskov said that Russia is “deeply concerned” about the deaths and claimed it had nothing to do with them, calling such a suggestion “quite absurd.”

“We continue to be deeply worried by the continuing presence of these poisonous substances on British territory,” Peskov said. “We consider that it is a danger not only for the British, but for other Europeans.”

Prime Minister Theresa May wrote on Twitter that she is “appalled and shocked” by the death.

British authorities have floated the possibility that the couple accidentally came across some of the batch of Novichok that was used to poison the Skripals.

“The possibility that the two investigations might be linked is clearly a key line of inquiry for police,” the London Metropolitan Police said in a statement.

So far, however, investigators have no concrete evidence that the two incidents are related.

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