Alexei Navalny has long been one of President Vladimir Putin's leading critics of the Russian government.
On August 20 this year came the news that Alexei Navalny fell ill on a plane en route from Siberia to Moscow.
In films taken on the plane and later posted on social media, Navalny could be heard screaming in pain.
Come in two days
He was first taken to a hospital in Omsk where he was in a coma for two days before being moved to a hospital in Berlin, after his family demanded that he be cared for outside Russia.
After investigations, it was stated that traces of poisoning had been found in Navalny's body.
Several laboratories, including a Swedish one, then examined the drug behind it and the results showed that it was the Soviet-developed neurotoxin novitjok that poisoned Navalny.
The same substance has been used against former Russian double agent Sergei Skripal and his daughter in the English city of Salisbury two years ago.
The Kremlin denies involvement
Alexei Navalny's employees later came out with the information that it is believed that he got the poison from a water bottle in the hotel room in Tomsk in Siberia.
On September 23, almost a month after the illness, Navalny is discharged from the hospital.
The Kremlin has denied any involvement in Navalny's poisoning.