Yulia Skripal, the poisoned daughter of Russian ex-spy Sergei, has been discharged from hospital, the BBC understands.
The 33-year-old was discharged from Salisbury District Hospital on Monday and taken to a secure location.
Her 66-year-old father remains in hospital but his condition is “improving rapidly”.
The pair were taken to hospital on 4 March after being exposed to the toxic nerve agent Novichok.
The father and daughter were found slumped on a park bench in the centre of Salisbury.
Wiltshire Police Det Sgt Nick Bailey, who attended the scene, was also treated in hospital after being exposed to the nerve agent, but has since been discharged.
A statement from Ms Skripal released through the Metropolitan Police last week said her “strength is growing daily”.
Doctors treating the pair said Mr Skripal was “responding well to treatment, improving rapidly and no longer in a critical condition”.
The UK government says Russia was behind the poisoning, and Prime Minister Theresa May said Moscow was “culpable” for attack.
But the Russian government denied any involvement and has accused the British of inventing a “fake story”.
Police said the pair first came into contact with the nerve agent at their home.
BBC security correspondent Gordon Corera said the highest concentration was found on the Skripals’ front door handle.
Traces of Novichok were also found at the Mill and Zizzi in Salisbury, where the Skripals spent the afternoon.
Investigators identified 131 people who had potentially been in contact with the nerve agent, and up to 500 people who visited the pub or the restaurant were told to wash their clothes and possessions.
Analysis: Long-term recovery
By BBC Health and Science Correspondent James Gallagher
Recovery from a nerve agent attack is not guaranteed, but it is not always a surprise either.
Nerve agents including Sarin, VX and Novichok all prevent nerves functioning normally. This includes those that are necessary to breathe and keep the heart beating.
They work by disrupting an enzyme called acetylcholinesterase at the junction between nerves.
But over time, the nerve agent is metabolised and excreted by the body and new acetylcholinesterase is made. The question is whether doctors can keep patients alive long enough for that to happen.
This would have been the focus of Sergei and Yulia Skripal’s care at Salisbury District Hospital. It could have included heart and lung support, the drug atropine to counteract the effect of nerve agents and sedation to prevent brain seizures.
There is still a question about the Skripals’ long term recovery and whether there will be any impact on memory and brain function.
Samples of the nerve agent have been tested by the Defence Chemical Biological Radiological and Nuclear Centre at Porton Down in Wiltshire, in an attempt to verify its source.
Its head said the precise source of the nerve agent had not been verified, but it was likely to have been deployed by a “state actor”.
A diplomatic crisis between Russia and the West has followed, with more than 20 countries expelling Russian envoys in solidarity with the UK.
Russia’s request for a new, joint investigation was voted down at the international chemical weapons watchdog at The Hague on 4 April.
Mr Skripal is a retired military intelligence officer who was convicted of passing the identities of Russian intelligence agents working in undercover in Europe to the UK’s Secret Intelligence Service, MI6.
He was jailed for 13 years by Russia in 2006, but was released in 2010 as part of an exchange for 10 Russian spies arrested by the FBI.
Ms Skripal regularly travelled from the UK and Moscow, and had returned from Russia the day before the pair were poisoned.