Traces of Novichok were found on a bottle of water where Alexey Navalny stayed in Tomsk, suggesting he was poisoned while in the Siberian city, and not from a cup of tea he drank at the airport as previously suspected.
The German government has said Navalny was poisoned with a chemical agent from the Novichok group, a conclusion supported by two other labs in France and Sweden.
The Russian opposition leader fell ill on a flight from Tomsk to Moscow on 20 August. The plane made an emergency landing in Omsk, where he spent two days in a coma before being flown by a medical jet to Berlin.
The German chancellor, Angela Merkel, said earlier this month that tests carried out in Germany showed “unequivocally” that the nerve agent was used to poison Navalny. Subsequent tests in France and Sweden have returned similar results.
The Organisation for the Prohibition of Chemical Weapons (OPCW), which is assisting German authorities in the case, said Thursday it was also running tests on samples collected from Navalny.
Russian authorities have repeatedly denied involvement in Navalny’s poisoning, either by claiming he was not poisoned at all or by claiming it could have been a “provocation”.
Novichok agents are both lethal and highly unusual, as a result, very few scientists outside of Russia have any real experience in dealing with them, raising questions about Moscow's role in the poisoning.
Earlier this week, the head of Russia’s foreign spy agency said Russia had already destroyed all its supplies of novichok, and that Navalny had no poison in his body when he was flown to Germany in a coma.
Novichok was used in a March 2018 attack on former Russian spy Sergei Skripal in the English city of Salisbury. It killed a British citizen, Dawn Sturgess.