MORE than 400 exhibits, samples and items have been recovered by search teams as part of the ongoing nerve agent investigation after the poisoning of Dawn Sturgess and Charlie Rowley.

Counter Terrorism detectives say searches are still expected to continue for several weeks, if not months, as officers look to identify any other potential sites or sources of contamination, as well as gather further evidence.

Yesterday, detectives announced they had recovered and identified a small bottle from Charlie Rowley's address in Muggleton Road, which they believe to have been the source of the contamination. 

Scientists have confirmed that the substance contained within the bottle was Novichok.

Dawn Sturgess and Charlie Rowley became ill on June 30 after coming into contact with the nerve agent.

Dawn died on Sunday and detectives launched a murder investigation. 

Assistant Commissioner Neil Basu, National Lead for Counter Terrorism (CT) Policing in the UK said: “It is not an exaggeration to say that the search process linked with both this and the Salisbury investigation has been one of the most complex and difficult that UK policing has ever faced.

“The work being carried out is extremely important. Not only are we trying to solve an extremely serious crime that has been committed, but we’re also working to identify any potential outstanding risks to the public; all whilst ensuring that all those involved in the search process are not themselves exposed to any risk of contamination.

“It is painstaking and vital work, which unfortunately takes a very long time to complete, but I am sure that the public understands why it is absolutely necessary.

"The scientists and forensic officers have all volunteered to be a part of the search teams, knowing that they are risking themselves to exposure to a deadly nerve agent. This shouldn't be taken for granted and their bravery and dedication is remarkable."

It takes search team members about 40 minutes to put on protective equipment and searches are limited to about 15-30 minutes due to the effects of heat and exhaustion. And it takes another 40 minutes to get out of the suits and complete the process.

Blood samples from everyone entering a scene are taken regularly and compared against a baseline sample to check for any signs of exposure to the nerve agent that they are working to find.

Typically, only two deployments per day can be carried out at any particular scene per day. 

More than 400 exhibits have been recovered as part of the Amesbury investigation and police say a significant number are potentially contaminated and have been submitted to DSTL labs for analysis.

Work is ongoing to establish whether the nerve agent is from the same batch used in the attack against Sergei and Yulia Skripal in March.