Investigators took almost four months to recover the bottle which contained the deadly novichok nerve agent for almost four months after it was used in an assassination attempt in Salisbury.
After it was placed on the front door of former double agent Sergei Skripal on 4 March 2018, a counterfeit Nina Ricci perfume bottle which was used to smuggle the nerve agent into the UK, was not recovered until 27 June.
Police believe two Russian men, Alexander Petrov and Ruslan Boshirov, then used a secret pump to spread the nerve agent on Mr Skripal's front door in March 2018.
The former Russian military intrelligence officer and his daughter Yulia were both left seriously ill and a further six people were exposed to novichok in Salisbury, which saw large swathes of it's town centre shut down as police investigated.
Nick Bailey, a police officer, also fell seriously ill after being exposed to the substance while investigating the case.
The source of the novichok was found almost four months later, after the death of Dawn Sturgess.
Ms Sturgess was given the perfume bottle as a gift by her partner Charlie Rowley, who had found it in a charity shop bin on 27 June 2018.
She died from exposure to the nerve agent three days later.
Mr Rowley fell seriously ill but later recovered.
The Metropolitan Police is continuing to appeal for anyone who saw the bottle, nozzle or box between 4 March and 27 June 2018 to come forward.
Blood samples taken from a “small number of people” feared to also have been exposed to the nerve agent in Salisbury were negative, investigators said.
“Counter terrorism detectives can confirm that forensic tests carried out on blood samples, which were taken from a small number of people back in March 2018, have found no traces of novichok,” a Metropolitan Police spokesperson said.
The people tested were contacted by detectives in August 2019, to seek permission for the examination to be carried out.
The tests were conducted after similar ones found traces of novichok in a blood sample taken from a second Wiltshire police officer.
The sample was taken in March 2018 and the result was confirmed in August 2019.
Detectives are continuing to appeal for information about the whereabouts of Alexander Petrov and Ruslan Boshirov between 2 and 4 March.
Additional reporting by agencies
