Her partner Charlie Rowley, 45, is still in a critical condition after the couple fell ill last Saturday.
According to the U.K.'s top anti-terrorism official, the A-234 Novichoknerve agent is the same chemical used in March on former Russian spy Sergei Skripal and his daughter Yulia just a few miles away in southwestern England.
The investigation into the nerve agent attacks is being led by Britain's Counter Terrorism Policing Network, and the police said around 100 detectives were working round the clock alongside colleagues from Wiltshire police. He said in a statement, "Dawn leaves behind her family, including three children, and our thoughts and prayers are with them at this extremely hard time".
Police investigating the incident say a murder investigation has now been launched in the wake of Ms Struggess death.
Defence Secretary Gavin Williamson blamed Russian Federation for committing "an attack on British soil" over the latest poisonings, some four months after Sergei and Yulia Skripal were targeted. The statement squarely pointed blame back at British intelligence and called for a joint investigation to be conducted by both governments.
"In the four months since the Skripals and Nick Bailey were poisoned, no other people besides Dawn and Charlie have presented with symptoms". Previously, Shulgin expanded on Russia's long-held thesis thatthe Novichok poisoning was an anti-Russian conspiracy.
Prime Minister Theresa May said she was appalled and shocked by the death.
Russian state television reports on July 9 nonetheless continued to cast doubt on the British investigations into the poisonings.
On Wednesday, the government's Defence Science and Technology Laboratory at Porton Down confirmed their exposure to Novichok.
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. "It is more of a British issue and the question is to what extent Great Britain is interested in conducting a real investigation", he noted.
Public Health England insists the overall risk to the public of being poisoned by the nerve agent is low.
A bus used by Mr Rowley and Ms Sturgess the night before they got ill has also tested negative for novichok.
The public has been warned that they should not pick up "any odd items such as needles, syringes or unusual containers".
Christine Blanshard, medical director at Salisbury District Hospital, where Sturgess and Rowley were being treated and where the Skripals were hospitalised, told The Daily Telegraph newspaper that staff had "worked tirelessly to save Dawn".
That poisoning sparked a tense diplomatic row between London and Moscow.