Counter terrorism police believe they have found the source of the Novichok nerve agent which poisoned a couple in Amesbury.
Dawn Sturgess, 44, died on Sunday after she was exposed to the substance, which also left her partner Charlie Rowley fighting for his life in hospital.
Police launched a murder inquiry following her death and had been combing the local area for the source of the poison - warning local residents not to pick up discarded containers.
In a statement on Friday, the Met Police said they had discovered a bottle containing Novichok in Rowley’s home.
“It was taken to the Defence, Science and Technology Laboratory (DSTL) at Porton Down, Wiltshire, for tests,” the force said.
“Following those tests, scientists have now confirmed to us that the substance contained within the bottle is Novichok.
“Further scientific tests will be carried out to try and establish whether it is from the same batch that contaminated Sergei and Yulia Skripal in March – this remains a main line of enquiry for police.
“Inquiries are under way to establish where the bottle came from and how it came to be in Charlie’s house.”
A post-mortem is due to take place next week to establish Sturgess’ cause of death and an inquest will be opened and adjourned on Thursday, July 19.
Assistant Commissioner Neil Basu, head of UK counter terrorism policing, said further traces of the substance could still remain in the area and urged people to continue to heed health warnings.
“This is clearly a significant and positive development. However, we cannot guarantee that there isn’t any more of the substance left and cordons will remain in place for some considerable time,” he added.
“This is to allow thorough searches to continue as a precautionary measure for public safety and to assist the investigation team.
“I also appreciate there is a lot of interest in this; however, we are not in a position to disclose any further details regarding the bottle at this stage.
“The safety of the public and our officers remains paramount and we are continuing to work closely with Wiltshire Police, scientists, health experts from Public Health England and other partners.”
Around 100 detectives from the Counter Terrorism Policing Network are continuing to work on the investigation, alongside Wiltshire Police officers.
Rowley, 45, regained consciousness earlier this week. Police said they had spoken “briefly” with him and will interview him further to establish how he and Sturgess came to be contaminated.
“This contact is being done in close consultation with the hospital and the doctors,” the Met statement said.
“The risk to the public in Salisbury and Amesbury remains low. We have not seen any further cases of illness linked to this incident.
“As a precaution Public Health England continues to advise the public not to pick up any strange items such as syringes, needles, cosmetics or similar objects made of materials such as metal, plastic or glass.
“The advice remains ‘if you didn’t drop it, then don’t pick it up’.”
A dedicated helpline - 0800 092 0410 - has been set up for anyone with health concerns in relation to this incident and anyone with information that may help the investigation is urged to contact counter terrorism police on 0800 789 321.