Charlie Rowley revealed he gave his partner Dawn Sturgess a sealed bottle – believing it was perfume – containing on “oily substance”, which she then sprayed on her wrists at his home in Amesbury.
As the investigation continues into Ms Sturgess’s death and the nerve agent attack in Salisbury, Sky News looks at some of the issues that are still to be resolved.
:: Where did Mr Rowley find the bottle of novichok?
Mr Rowley says he does not remember where he found the perfume box which contained the toxic chemical.
He says his memory has been affected after being exposed to the nerve agent.
He is convinced, however, that he did not find the bottle in a park in Salisbury, where former Russian spy Sergei Skripal and his daughter Yulia were poisoned.
Mr Rowley says he believes he may have picked up the bottle a couple of days before falling ill.
:: What brand of perfume bottle was the novichok hidden in?
The brand of perfume bottle that contained the novichok has not been revealed by police.
Mr Rowley has also not spoken publicly about the brand, only saying that Ms Sturgess recognised it and the bottle “looked expensive”.
:: Are there other bottles of novichok that are still to be found?
Police say they cannot guarantee there is no more novichok in Wiltshire.
Paul Mills, deputy chief constable for Wiltshire Police, told Sky News: “I cannot guarantee there is not something else out there.”
:: Was the novichok in Amesbury the same nerve agent used against the Skripals?
One theory being investigated was that the novichok used in the Skripal poisoning was in a container that Ms Sturgess and Mr Rowley found and opened.
But doubt has been cast on that theory after Mr Rowley confirmed he unwittingly found the nerve agent in an unopened glass bottle that was in a cardboard box wrapped in plastic moulding.
The Metropolitan Police, which is leading the investigation, says it has not been able to determine whether the novichok in Salisbury and Amesbury was from the same batch.
:: How was the novichok brought into the UK?
Sky’s crime correspondent Martin Brunt says it is the government’s long-held belief that the Russian state was behind the attack on the Skripals, or at least had lost control of the nerve agent novichok – which scientists say is made only in Russia.
But authorities have not revealed how they believe the nerve agent was smuggled into the country.
Andy Oppenheimer, a biological and chemical specialist, told Sky News the chemical could have been brought into the UK through an airport.
“These things can evade detection if they are very small amounts and very well shielded, whether they are biological, chemical or a biological agent,” he says.
“This chemical may have come through an airport, we really don’t know yet.”
:: Who is responsible for the poisonings in Amesbury and Salisbury?
Police believe they have identified the suspected perpetrators of the Skripal poisonings, a source has told the Press Association news agency.
The Met Police has declined to comment and security minister Ben Wallace dismissed the report as “wild speculation”.
Officers believe several Russians were involved in the attempted murder and they are looking for more than one suspect.