Salisbury police officer DS Nick Bailey was also left seriously ill after coming into contact with it at the Skripal's house.
Four months after that, in July 2018, Dawn Sturgess died after spraying the substance onto her skin, believing it to be perfume.
Her partner, Charlie Rowley, had found a bottle containing novichok in a bin and given it to Dawn. He was also hospitalised after the exposure, but has since recovered.
Two men identified as suspects for carrying out the attack, Alexander Petrov and Ruslan Boshirov, went on Russian state-funded TV in September last year to claim they had only travelled to Salisbury as tourists, to visit its famous cathedral.
Wiltshire Police are aware of the situation.
Salisbury Cathedral was completed in 1258 and has the tallest spire in England - which measures 123m.