"Police and security officials are working urgently to establish the facts of this incident, which is now being investigated as a murder", she added.
The head of UK Counter Terrorism policing, Assistant Commissioner Neil Basu, said Sturgess, a mother of three, died as the result of "an outrageous, reckless and barbaric act".
"It is both shocking and utterly appalling that a British citizen has died having been exposed to a Novichok nerve agent but make no mistake we are determined to find out how Dawn and her partner Charlie came into contact with such a deadly substance", Basu said.
The Minister of Interior, Sajid Javid, asked on Thursday explanations to Russian Federation by poisoning of Rowley and Sturgess, four months after government blamed Moscow for attack on Skripal.
Russian Federation has repeatedly denied any involvement in the Skripal incident and offered to participate in a related investigation.
Police have launched a murder investigation.
Ms Sturgess collapsed at about 10.15am on 30 June and was taken to hospital in an ambulance.
Sturgess died at Salisbury District Hospital, the same facility that nursed the critically ill Skripals.
He said no one else in the area has shown any sign of Novichok poisoning.
Abortion Groups Protest Kavanaugh, Launch Ad Campaign Targeting Vulnerable Republicans
Cuomo says Monday that the GOP-led Senate should immediately reconvene to pass the measure in light of a vacancy on the U.S. As for what he says about NY law being tougher on abortion than Roe , that's marginally true.
Amber Rudd, Mr Javid's predecessor who resigned in April, had previously visited the site in Salisbury where Russian ex-spy Mr Skripal and his daughter were poisoned with Novichok.
Defense Secretary Gavin Williamson blamed Russian Federation for the "Novichok death" but police said they have no evidence to connect the Salisbury poisoning in March and the Sturgess poisoning Sunday.
Police are working on the theory that Ms Sturgess and Mr Rowley came across an item used to dispense the Novichok and discarded by the would-be assassin or assassins of the Skripals.
"Our focus and priority at this time is to identify and locate any container that we believe may be the source of the contamination", Basu said.
One line of inquiry suggests that after the Skripals were attacked by the nerve agent, the assailants disposed of vials, ampules or a mixing kit - or some other contaminated items - and that Rowley and Sturgess found the material and were accidentally exposed.
"We consider that it is a danger not only for the British, but for other Europeans", he said.
Last week, the Chief Medical Officer for England said that the risk to the wider public remains low but that people in the local area should not pick up any odd items such as needles, syringes or unusual containers, given the source of the contamination has not yet been found.
A red transit van that Mr Rowley travelled in the day he fell ill has been identified and taken to Porton Down where tests will be carried out.