2010 - Sergei Skripal, a former Russian military intelligence officer jailed for spying for Britain, is released and flown to the UK as part of a swap with Russian agents caught in the United States. He settles in Salisbury.

March 3, 2018 - Yulia Skripal arrives at Heathrow Airport from Russia to visit her father in England.

March 4, 9.15am - Sergei Skripal's burgundy BMW is seen in suburban Salisbury, near a cemetery, where his wife and son are commemorated.

March 4, 1.30pm - The BMW is seen driving toward central Salisbury.

March 4, 1.40pm - The BMW is parked at a lot in central Salisbury.

A police officer stands guard outside the Zizzi restaurant where Sergei and Yulia had lunch before they collapsed in a nearby park

March 4, afternoon - Sergei and Yulia Skripal visit the Bishops Mill pub.

March 4, 2.20pm to 3.35pm - Sergei and Yulia Skripal have lunch at the Zizzi restaurant.

March 4, 4.15pm - Emergency services are called by a passer-by concerned about a man and a woman in Salisbury city centre.

Officers find the Skripals unconscious on a bench. They are taken to Salisbury District Hospital, where they remain in critical condition.

March 5, morning - Police say two people in Salisbury are being treated for suspected exposure to an unknown substance.

March 5, afternoon - Wiltshire Police, along with Public Health England, declare a 'major incident'

March 7 - Police announce that the Skripals were likely poisoned with a nerve agent in a targeted murder attempt.

They disclose that a police officer who responded to the incident is in serious condition in a hospital.

March 8 - Home Secretary Amber Rudd describes the use of a nerve agent on UK soil was a 'brazen and reckless act' of attempted murder

March 9 - About 180 troops trained in chemical warfare and decontamination are deployed to Salisbury to help with the police investigation.

Russian Foreign Minister Sergey Lavrov says Moscow might be willing to assist with the investigation but expresses resentment at suggestions the Kremlin was behind the attack.

March 11 - Public health officials tell people who visited the Zizzi restaurant or Bishops Mill pub in Salisbury on the day of the attack or the next day to wash their clothes as a precaution.

March 12, morning- Prime Minister Theresa May tells the House of Commons that the Skripals were poisoned with Novichok, a military-grade nerve agent developed by the Soviet Union during the Cold War.

March 12, afternoon - Public Health England ask everyone who visited Salisbury town centre on the day of the attack to wash all of their clothes and belongings.

Officers wearing chemical protection suits secure the forensic tent over the bench where Sergei and Yulia fell ill

March 14 - The PM announces the expulsion of 23 suspected Russian spies from the country's UK Embassy.

March 22 - Nick Bailey, the police officer injured in the attack, is released from hospital.

March 26 - The United States and 22 other countries join Britain in expelling scores of Russian spies from capitals across the globe.

March 29 - Doctors say Yulia Skripal is 'improving rapidly' in hospital.

'Unknown time in the spring' - Dutch authorities expelled two suspected Russian spies who tried to hack into a Swiss laboratory

April 3 - The chief of the Porton Down defence laboratory said it could not verify the 'precise source' of the nerve agent.

April 5, morning - Yulia Skripal's cousin Viktoria says she has received a call from Yulia saying she plans to leave hospital soon.

Dawn Sturgess died in hospital on July 8

April 5, afternoon - A statement on behalf of Yulia is released by Metropolitan Police, in which she says her strength is 'growing daily' and that 'daddy is fine'.

April 9 - Ms Skripal is released from hospital and moved to a secure location.

May 18 - Sergei Skripal is released from hospital 11 weeks after he was poisoned.

June 30 - Dawn Sturgess and Charlie Rowley fall ill at a property in Amesbury, which is eight miles from Salisbury, and are rushed to hospital.

July 4 - Police declare a major incident after Ms Sturgess and Mr Rowley are exposed to an 'unknown substance', later revealed to be Novichok.

July 5 - Sajid Javid demands an explanation over the two poisonings as he accuses the Russian state of using Britain as a 'dumping ground for poison'.

July 8 - Mother-of-three Dawn Sturgess, 44, dies in hospital due to coming into contact with Novichok.

July 10 - Mr Rowley regains consciousness at hospital, and later tells his brother that Dawn had sprayed the Novichok onto her wrists.

July 19 - Police are believed to have identified the perpetrators of the attack.

August 20 - Charlie Rowley is rushed to hospital as he starts to lose his sight, but doctors can't confirm whether it has anything to do with the poisoning.

August 26 - Charlie Rowley admitted to intensive care unit with meningitis

August 28 - Police call in the 'super recognisers' in bid to track down the poisoners

September 4 - Charlie Rowley's brother says he has 'lost all hope' and doesn't have long to live.

Independent investigators, the Organisation for the Prohibition of Chemical Weapons, confirm the toxic chemical that killed Ms Sturgess was the same nerve agent as that which poisoned the Skripals.

September 5 - Scotland Yard and CPS announce enough evidence to charge Russian nationals Alexander Petrov and Ruslan Boshirov for conspiracy to murder over Salisbury nerve agent attack.

September 13 - Britain's most wanted men speak to RT and claim to be humble tourists

September 26 - The real identity of one of the two assassins, named by police as Ruslan Boshirov, is reported to be Colonel Anatoliy Vladimirovich Chepiga.

October 3: New photo emerges that appears to show Col Chepiga on the Wall of Heroes at the Far-Eastern Military Academy, providing more evidence against the Kremlin's denials.