Sergei Skripal, a former double intelligence agent for Russia and Britain, was taken critically ill after being exposed to a mystery substance.
He and his daughter Yulia collapsed on a bench in Salisbury, south England, on Sunday. They remain in critical condition.
The case has sparked wild speculation that Skripal was targeted by Russian assassins, but the Kremlin has denied any knowledge.
In a mark of how serious the matter is being taken by UK authorities, counterterrorism police are now leading the investigation into the apparent poisoning.
Scroll down to learn more about Skripal, and see exactly how he went from working for Russian intelligence to fighting for his life at a hospital in Britain.
Sergei Skripal, who’s now 66, started passing Russian state secrets to the UK in 1990s. Not much is known about his life before that.
1995 — British spies recruit Skripal while he is a Russian military intelligence officer. He starts passing Russian state secrets to Britain’s Secret Intelligence Service, also known as MI6.
Oli Scarff / Getty
His leaks include the identities of dozens of Russian agents in Europe. This information is later used to surveil and later expel the agents from multiple European countries.
- UK counter-terror police are now leading the investigation into the suspected poisoning of a former Russian spy
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