Nerve agent
Russian Embassy accuses government of trying to “muddy the waters”.
Officers have scoured more than 4,000 hours of CCTV footage.
Treating the Skripals has been a 'huge and unprecedented challenge', the hospital said.
The agent could be applied with an aerosol spray or transported in liquid form.
A 'very small amount' of the nerve agent was used in the attack.
Boris Johnson says it proves Russia was behind it.
Her father Sergei should be able to leave 'in due course'.
'It’s Russia’s response that has been unsatisfactory'.
'A rich buffet of nonsense.'
Persian cat named Nash Van Drake found 'very unwell' at Skripal's Wiltshire home.