Counter terrorism detectives believe they may have found the source of the deadly nerve agent Novichok which left one person dead and another seriously ill.
Mother-of-three Dawn Sturgess, 44, and her partner Charlie Rowley, 45, were exposed to the substance last month. Ms Sturgess died, while Mr Rowley remains seriously ill in hospital.
On Friday, New Scotland Yard revealed that searches of Mr Rowley’s home in Amesbury had turned up a small bottle – and that lab tests carried out by the nearby Defence, Science and Technology Laboratory at Porton Down confirmed it contained Novichok.
Jerry Smith, a former chemical weapons inspector, told ITV News the find was “important”.
“A piece of evidence that was actually used in the attempted assassination may mean there is evidence for the police investigation to follow up, such as DNA or fingerprints.
“And of course, having some more of the material … from a forensics point of view, with regards to the chemical analysis, would also be important.”
The UK has now invited experts from the Organisation for the Prohibition of Chemical Weapons (OPCW) to independently confirm the identity of the nerve agent.
Further scientific tests will be carried out to try to establish whether it is from the same batch that contaminated Sergei and Yulia Skripal in March.
Inquiries are also underway to establish where the bottle came from, and how it came to be in Mr Rowley’s home.
A post mortem examination of Ms Sturgess is scheduled to take place on Tuesday, while an inquest into her death is expected to open and adjourn in Salisbury on Thursday.