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.
Counter terrorism investigators said they had recovered a small glass bottle from the home of victim, Charlie Rowley, which had tested positive for Novichok.
The Novichok saga began in March when Sergei and Yulia Skripal mysteriously fell ill on a park bench in Salisbury.
"Following those tests, scientists have now confirmed to us that the substance contained within the bottle is Novichok".
Neil Basu, head of United Kingdom counter-terrorism policing, said: "This is clearly a significant and positive development".
Her husband, Mr Rowley has since regained consciousness but remains in serious condition, as hospital staff continue to treat him. "However, we can not guarantee that there isn't any more of the substance left and cordons will remain in place for some considerable time", Metropolitan Police Assistant Commissioner Neil Basu said in a statement.
The UK has invited experts from the Organisation for the Prohibition of Chemical Weapons to independently confirm the identity of the nerve agent.
He declined to give further details on the bottle, but police said inquiries were ongoing to establish where the bottle came from and how it came into Rowley's possession.
A post-mortem examinaton will be conducted next Tuesday to investigate Ms Sturgess' death.
The search for the container was conducted by officers from Scotland Yard's counter-terrorism command.
Further scientific tests will determine whether the toxic nerve agent came from the same batch that contaminated former Russian spy Sergei and his daughter, Yulia Skripal in March. They have since been discharged from hospital.