UK police identify Salisbury suspects
Police and intelligence agencies in the UK have identified key suspects in the attempted assassination of Sergei Skripal and his daughter Yulia.
Counter-terrorism police are building a case against "persons of interest", who are believed now to be in Russia.
It is thought that a search of flight manifests in and out of the UK has yielded specific names in the hunt for the Skripals' would-be assassins.
Police have also drawn on CCTV footage.
However, counter-terrorism police will hit a diplomatic brick wall in trying to interview - let alone prosecute - the suspects.
Investigators privately admit the difficulties in bringing charges, while any demands made by authorities for access to the "persons of interest" will further ratchet up tensions between the UK and Russia.
Authorities believe Col Skripal (66), a Russian double agent who spied for Britain, was targeted at his home by a Kremlin-backed hit squad that smeared the Novichok nerve agent on his front door.
The emails of Yulia Skripal (33), who lives in Moscow, were monitored prior to her flight to the UK to visit her father, giving the hit squad notice of when he would be at home.
The decontamination of Salisbury began in earnest yesterday with cordons in place in nine "hot spots". Officials insisted the city is still safe for residents and visitors.