A man who was accidentally exposed to novichok has regained consciousness two days after his partner died.
Officials at Salisbury District Hospital said Charlie Rowley’s condition had improved but warned he is “not out of the woods yet”.
Police believe the 45-year-old and his partner, Dawn Sturgess, handled a “container” of the nerve agent and are still hunting for the item, sparking a warning for local people not to pick up anything containing a liquid or gel.
Lorna Wilkinson, the director of nursing at Salisbury District Hospital, said there had been a “small but significant improvement” in Mr Rowley’s condition.
“He is in a critical but stable condition, and is now conscious,” she added. “While this is welcome news, clearly we are not out of the woods yet. Charlie is still very unwell and will continue to require specialist, round-the-clock care.”
Investigators’ main line of inquiry is whether the couple came into contact with the same novichok used against former Russian double agent Sergei Skripal and his daughter.
They survived the poisoning in March, when nerve agent was spread on Mr Skripal’s front door, and have both since been discharged from hospital to recover in secret locations.
Police said Ms Sturgess’s death, which was announced on Sunday night, meant she and Mr Rowley were subjected to a strong dose of the chemical weapon.
“Our focus and priority at this time is to identify and locate any container that we believe may be the source of the contamination,” said Assistant Commissioner Neil Basu, the head of UK counterterror policing.
“[Ms Sturgess and Mr Rowley] must have got a high dose and our hypothesis is that they must have handled a container we are now seeking.”
People in the Amesbury and Salisbury areas have been warned not to “pick up any foreign object which could contain liquid or gel” as the search continues.
Officials confirmed Ms Sturgess and Mr Rowley had touched a contaminated item with their hands, raising fears that others could fall victim to the chemical weapon – especially during the school summer holidays.
Police and health officials will seek to address safety concerns at a public meeting in Amesbury tonight, amid shock over Ms Sturgess’s death.
Dame Sally Davies, the chief medical officer, said: “Do not pick up containers, syringes, needles, cosmetics or similar objects, made of materials such as metal, plastic or glass.
“This is particularly important as families are starting to prepare for their children’s summer holidays and so I am asking that people are extra vigilant. To be clear: do not pick up anything that you haven’t dropped yourself.”
Friends of Mr Rowley said he was known to forage for goods to fix and sell, and he and Ms Sturgess are known to have collected discarded cigarettes.
Dame Sally emphasised that the overall threat to the wider public remains low and said areas decontaminated following the attack on the Skripals are safe.
“You do not need to seek advice from a health professional unless you are experiencing symptoms,” she added. “If you are concerned, you should call NHS 111 and Wilshire Police has also established a helpline to offer further advice: 0800 092 0410.”
More than 20 people, including a police officer, have presented themselves to authorities with concerns but all have tested negative for nerve agent exposure.
The supported-living accommodation where Ms Sturgess lived in Salisbury has been cordoned off alongside Mr Rowley’s home in Amesbury, where they both fell ill.
Other areas they visited on 29 and 30 June, including a park, are also being investigated by police in protective clothing.
A car belonging to an emergency services worker has been seized for testing in Swindon, as well as a red Ford Transit van Mr Rowley travelled in before falling ill.
A bus that Ms Sturgess and Mr Rowley used to travel from Salisbury to his home in Amesbury the night before they collapsed has also tested negative for novichok.
Officials said the couple had not visited areas of Salisbury that had been frequented by the Skripals and subsequently decontaminated. Security services hope that tracing the container will provide vital clues.
Relatives of Ms Sturgess, who had three children, have urged the public to “stop speculating” about her death.
“Dawn will always be remembered by us as a gentle soul who was generous to a fault,” a statement added.
“She would do anything for anybody and those who knew Dawn would know that she would gladly give her last penny to somebody in need.
“She had the biggest of hearts and she will be dreadfully missed by both her immediate and wider family.”
Angus Macpherson, police and crime commissioner for Wiltshire, said Ms Sturgess was an “innocent member of the public who should have been able to go about her daily life without becoming an unwilling victim in such an unprecedented, international, incident”.
Emergency services initially treated the couple’s illness as drug-related because of information from a friend, their symptoms and items found at Mr Rowley’s home.
Wiltshire Police Chief Constable Kier Pritchard defended the response as “entirely proportionate” last week and gave his support to those initial responders.
But medics at Salisbury District Hospital became concerned about Ms Sturgess and Mr Rowley’s symptoms and sent samples to the Porton Down defence laboratory for analysis.
When they came back indicating nerve agent exposure, a major incident was declared.
Sajid Javid, the home secretary, told MPs that Ms Sturgess’s death “only strengthens our resolve to find out exactly what happened and who is behind it”.
Gavin Williamson, the defence secretary, blamed Russia for committing “an attack on British soil” over the latest poisonings, four months after Mr Skripal and his daughter were targeted.
“The simple reality is that Russia has committed an attack on British soil which has seen the death of a British citizen,” he told MPs. “That is something that I think the world will unite with us in actually condemning.”
The Kremlin has denied any involvement in the attack on former double agent Mr Skripal or the latest incident, claiming that linking Russia to the poisoning would be “absurd”.