As reported by Censor.NET citing ITV News media outlet, a source with knowledge of the investigation told the Press Association: "Investigators believe they have identified the suspected perpetrators of the Novichok attack through CCTV and have cross-checked this with records of people who entered the country around that time.
"They (the investigators) are sure they (the suspects) are Russian."
Investigators are working to the theory that the substance was in a discarded perfume bottle found by Dawn Sturgess, 44, and her partner Charlie Rowley, 45 in a park or somewhere in Salisbury city centre, the source said.
It is thought Ms Sturgess sprayed the Novichok straight on to her skin as it is understood she was exposed to at least 10 times the amount of nerve agent the Skripals came into contact with.
Ms Sturgess fell ill on the morning of June 30 and died eight days later in Salisbury District Hospital, while Mr Rowley was left fighting for his life after also becoming contaminated.
An inquest into her death was opened by the Wiltshire and Swindon Coroner in Salisbury on Thursday, with her body released to her family for a funeral. It was adjourned until January.
"The cause of death will not be given until further tests are completed," coroner David Ridley said.
The inquest heard that a "small glass bottle of fluid" containing Novichok had been found at Mr Rowley’s home in Muggleton Road, Amesbury.
Counter-terrorism officers are trying to establish where the container came from, and how it came to be in his house.
As reported, Russian ex-spy Sergei Skripal, 66, and daughter Yulia Skripal, 33, remain critically ill in hospital, after they were found unconscious on a bench in the Wiltshire city on March 4. The UK government says they were poisoned with a nerve agent of a type developed by Russia called Novichok and PM Theresa May said she believed Moscow was "culpable."
UK expelled 23 Russian diplomats as part of a "full and robust" response – prompting Russia's Foreign Minister Sergei Lavrov to say it will "certainly" expel British diplomats in response.
On March 16, Nato Secretary General Jens Stoltenberg said the alliance had "no reason to doubt the findings and assessments by the British government" which suggested Russian responsibility. He said the "UK is not alone" and Nato allies gave "strong political support" to Britain, following a joint statement from the US, France and Germany backing Mrs May's government and a pledge of support from Australia.
British Foreign Minister Boris Johnson said that the U.K.'s government believes that it was likely Putin's decision to direct the use of a nerve agent on the streets of the U.K.
On March 26, U.S. President Donald Trump ordered the expulsion of 60 Russians from the United States, including 12 people identified as Russian intelligence officers who have been stationed at the United Nations in New York.