A British woman exposed to the Russian nerve agent Novichok has died

British police launched a murder investigation Monday after a woman in Western England died from exposure to the Russian nerve agent Novichok.

Dawn Sturgess, 44, from Durrington, passed away on Sunday night in hospital in Salisbury more than a week after she was admitted showing symptoms associated with exposure to the highly toxic poison.

Sturgess’s partner, Charlie Rowley, 45, remains in critical condition. Both were admitted to the hospital where former Russian spy Sergei Skripal and his daughter Julia were treated for Novichock poisoning in March.

A postmortem is due to take place Monday. Police are still trying to piece together how the pair came into contact with the poison, but they have confirmed Sturgess and Rowley touched a contaminated item with their hands.

"This is shocking and tragic news,” Neil Basu, head of U.K. counterterrorism policing, said in a statement Sunday. “Dawn leaves behind her family, including three children, and our thoughts and prayers are with them at this extremely difficult time.”

Basu described the incident as an “outrageous, reckless, and barbaric act.”

Last week U.K. security minister Ben Wallace called on Moscow to “fill in some of the significant gaps we are trying to pursue,” but on Sunday Home Secretary Sajid Javid said the government would not at this point be extending sanctions against Moscow, following Sturgess’s death.

“We don’t want to jump to conclusions,” Javid said during a visit to Salisbury. “We know back in March that it was the Russians. We know it was a barbaric, inhuman act by the Russian state. Again, for this particular incident, we need to learn more and let the police do their work.”

Prime Minister Theresa May said she was “shocked and appalled” at the news of Sturgess’s death, adding: “Police and security officials are working urgently to establish the facts of this incident, which is now being investigated as a murder.”

Following the Skripals' poisoning, the U.K. expelled 23 Russian diplomats and suspended all planned high-level bilateral contacts. In response, Moscow expelled the equal number of U.K. diplomats.

Moscow has yet to respond to the latest poisoning, but the Kremlin has consistently denied any involvement, claiming it is a “fake story” concocted by the U.K. government.

Cover image: Emergency workers in protective suits search around John Baker House Sanctuary Supported Living after a major incident was declared when a man and woman were exposed to the Novichok nerve agent on July 6, 2018 in Salisbury, England. (Jack Taylor/Getty Images)