The Novichok poisonings inquiry will look at whether an “innocent” British woman died after she was caught in the “crossfire of an illegal and outrageous international assassination attempt”.
Dawn Sturgess, 44, died after being exposed to the Russian nerve agent which was left in a discarded perfume bottle in Amesbury, Wiltshire, in July 2018.
It followed the attempted murders of former spy Sergei Skripal, his daughter Yulia and then-police officer Nick Bailey, who were poisoned in nearby Salisbury in March that year.
All three survived, as did Ms Sturgess’s boyfriend, Charlie Rowley, who had unwittingly given her the bottle containing the killer nerve agent.
Mr Skripal believes Russian President Vladimir Putin was responsible for poisoning him with Novichok, the inquiry heard on Monday.
In an interview in May 2018, a police officer put it to him that he believed President Putin was responsible, to which he replied “It’s my private opinion”, said Andrew O’Connor KC, counsel to the inquiry.
Mr O’Connor also said Jonathan Allen, a senior FCDO official, provided the inquiry with a statement in which he said it is the Government’s view that Mr Putin “authorised the operation”.
An international arrest warrant was issued for three Russian men thought to be involved in the attacks on British soil, but as the Russian constitution does not allow the extradition of its citizens, it is unlikely they will ever stand trial.
Mr O’Connor said on Monday: “It’s no exaggeration to say the circumstances of Dawn Sturgess’s death were extraordinary, they were indeed unique.”
“When Ms Sturgess was poisoned by Novichok four months after the Skripal poisoning, the real possibility emerged that she had been caught – an innocent victim – in the crossfire of an illegal and outrageous international assassination attempt.
“Whether or not that is in fact what happened will, of course, be for you to determine.”
The perfume bottle carrying Novichok that fatally poisoned Ms Sturgess contained “enough poison to kill thousands of people”, the inquiry was told.
Mr O’Connor said: “A particularly shocking feature of Dawn’s death is that she unwittingly applied the poison to her own skin.
“Moreover, the evidence will suggest that this bottle – which we shall hear contained enough poison to kill thousands of people – must earlier have been left somewhere in a public place, creating the obvious risk that someone would find it and take it home.
“You may conclude, sir, that those who discarded the bottle in this way acted with a grotesque disregard for human life.”
After her death, Mr Rowley described Ms Sturgess as “a lovely lady, she had a big heart, she’d help anyone if she could” and her mother said Ms Sturgess was “the happiest she’d been for a long time”, the inquiry heard.
Ms Sturgess suffered from long-term dependence on alcohol, but in the months before her death was “settled and happy”.
He added that the family wish to know “whether any of the things that may have gone wrong in Dawn’s treatment could have made a difference to her chances of survival”, adding: “To use a legal term – if there were failings, were they causative?”
The inquiry was also told Mr Skripal was born in Russia and served as a paratrooper and later as a member of the GRU – Russian military intelligence.
He was convicted in Russia on espionage charges in 2004, he was alleged to have spied for Britain, Mr O’Connor said.
Mr Skripal was sentenced to 13 years in prison, but in 2010 he was given a presidential pardon and brought to the UK on a prisoner exchange, he added.
He had lived in Salisbury since 2010.
The inquiry will look into whether the UK authorities took appropriate precautions in early 2018 to protect Mr Skripal from being attacked.
Mr O’Connor said the fact that Mr Skripal was a former senior GRU officer living in the UK “arguably placed him at some risk”.
He added that Mr Skripal recognised this himself in a police interview in 2018, in which he said: “I am a very important man of special services. Still now I know a lot of Russian secrets, top secrets, they are really dangerous for Russian special services.”
The inquiry will also examine whether the poisoning of Ms Sturgess could have been prevented.
It was previously revealed that the Skripals would not give evidence at the inquiry amid fears for their safety.
It comes as Wiltshire Police said people in Salisbury city centre can expect to see an increased police presence for the duration of the hearing.
They added that there is “no current intelligence to suggest there is any risk to the wider public”.
The Dawn Sturgess Inquiry, chaired by former Supreme Court judge Lord Hughes of Ombersley, opened at the Guildhall in Salisbury and will continue until December.