Video report by ITV News Security Editor Rohit Kachroo
One of the two suspects in the Salisbury poisoning case could give his side of the story as early as next week, according to Russian media.
State TV channel Rossiya-24 claimed it had spoken to Alexander Petrov, who, along with Ruslan Boshirov, has been named by UK prosecutors as a prime suspect in the nerve agent attack.
On Wednesday, the station reported Petrov, who is said to live in Siberia, as saying he would "maybe" give an interview next week.
It comes after Russian president Vladimir Putin broke his silence on the two men, believed to be members of the GRU, when he claimed there was "nothing criminal" about them.
The Russian leader went on to invite Petrov and Boshirov to appear in public and talk about themselves.
Mr Skripal and his daughter Yulia were left in comas for weeks after being exposed to the nerve agent Novichok, while Dawn Sturgess later died and Charlie Rowley was left in a critical condition after they too came into contact with the substance in nearby Amesbury.
CCTV footage from early March shows Petrov and Boshirov arriving at Heathrow Airport from Russia, and also in the vicinity of Sergei Skripal's house on the day of the attack.
Russia has hotly contested the allegations that it is responsible for the attack, and Mr Putin escalated the war of words by denying the men were members of military intelligence, and that his officials “know who these people are”.
"Of course, we looked at who these people are," Mr Putin said.
"We know who they are. We have found them already. Ihope that they will emerge and tell us about themselves.
"It will be better for everybody."
His intervention risks widening the gulf between Russia and the UK over the attempted assassination, which triggered a wave of diplomatic expulsions by both sides.
Detectives believe it is likely the two suspects, thought to be aged around 40, travelled under aliases and that Petrov and Boshirov are not their real names.
Mr Skripal was a former GRU agent, before defecting and aiding the UK.
Prosecutors deem it futile to apply to Russia for the extradition of the two men, since Moscow does not extradite its own citizens, but a European Arrest Warrant has been obtained and the authorities are also seeking the assistance of Interpol.
While police and prosecutors have announced they have enough information to charge Boshirov and Petrov, and officers have formally linked the attack on the Skripals to the poisoning of Ms Sturgess and Mr Rowley, the charges do not relate to the Amesbury pair and authorities say they are still investigating this second incident.
A police officer who visited the home of the Skripals shortly after the attack, Nick Bailey, was also left critically ill from exposure to the substance.
Suspect's movements up to and following poisoning
At 3pm on Friday, March 2, the suspects arrive at Gatwick airport, having flown from Moscow on Aeroflot flight SU2588, two days before the attack.
They then travel by train into London, arriving at Victoria station at approximately 5.40pm.
They travel on London public transport to Waterloo station the travel to the City Stay Hotel in Bow Road, East London, where they stayed on Friday, 2 March, and Saturday, March 3.
On Saturday, March 3, they leave the hotel and take the underground to Waterloo station, where they caught a train to Salisbury, arriving at approximately 2.25pm. It is believed this trip was for reconnaissance of the Salisbury area there was no risk to the public from their movements on this day.
They take the same route when they return to London on the afternoon of Saturday, March 3. Leaving Salisbury at approximately 4.10pm and arriving in Bow at approximately 8.05 pm.
On Sunday, March 4, they make the same journey from the hotel, again using the underground from Bow to Waterloo station at approximately 8.05am, before continuing their journey by train to Salisbury.
CCTV shows them in the vicinity of Mr Skripal’s house and it is believed they contaminated the front door with Novichok.
They leave Salisbury and return to Waterloo Station, arriving at approximately 4.45pm and board the London Underground at approximately 6.30pm to London Heathrow Airport.
From Heathrow Airport, they return to Moscow on Aeroflot flight SU2585, departing at 10.30pm on Sunday, March 4.