Dawn Sturgess, 44, from Durrington, died on Sunday evening at the Salisbury district hospital, after handling an item contaminated with the nerve agent on June 30, reports the Guardian.
Her partner Charlie Rowley, 45, who was also taken ill after being exposed to the nerve agent, remains in a critical condition in hospital.
The investigation is being led by detectives from the Counter Terrorism Policing Network, with about 100 other detectives.
Investigators are still trying to determine how the couple were exposed to the nerve agent after emergency services were called to a residential address in Amesbury after Sturgess collapsed.
Later the same day, an ambulance was called back to the address after Rowley fell ill.
Following Sturgess's death, Assistant Commissioner Neil Basu, head of UK counter-terrorism policing, said on Sunday night: "This is shocking and tragic news. Dawn leaves behind her family, including three children, and our thoughts and prayers are with them at this extremely difficult time.
"This terrible news has only served to strengthen our resolve to identify and bring to justice the person or persons responsible for what I can only describe as an outrageous, reckless and barbaric act."
Counter-terrorism officers are still investigating the attempted murders Skripal and his daughter, Yulia, who were poisoned in March in Salisbury, the Guardian reported.
Responding to the death, Prime Minister Theresa May said: "I am appalled and shocked by the death of Dawn Sturgess... Police and security officials are working urgently to establish the facts of this incident, which is now being investigated as a murder."
(This story has not been edited by Social News XYZ staff and is auto-generated from a syndicated feed.)
