The Novichok poisoning in Salisbury has claimed its first victim as Dawn Sturgess died eight days after coming into contact with the Russian nerve agent.

Police are treating the death of the 44-year-old mother of three on Sunday night as murder, describing the tragedy as “the day we hoped would never come”. Her partner Charlie Rowley, 45, is still in a critical condition after the couple fell ill last Saturday.

The murder investigation is the second major probe involving the nerve agent this year, following the case of Sergei and Yulia Skripal, who were left critically ill in March. Both have recovered.

Tests have revealed that Ms Sturgess and Mr Rowley were exposed to the nerve agent after touching a contaminated item with their hands.

The possibility that the two investigations might be linked is "clearly a key line of inquiry for police", the Met said.