TOMSK, Russia—Shortly after Russian opposition leader Alexei Navalny collapsed last month on a plane over Siberia with signs of poisoning, his supporters rushed to the hotel room where he had been staying to look for clues.
Instead of calling the police, they said they bagged everything they could find there in the hopes of solving the mystery of what struck down the 44-year-old activist.
Days later, German doctors who were treating Mr. Navalny, a critic of Russian President Vladimir Putin, determined that the opposition politician had been poisoned by Novichok, a military-grade nerve agent.
Who administered the toxin to Mr. Navalny, how it was dispensed and where all remain unclear.
With little faith in Russia’s law enforcement agencies, Mr. Navalny’s supporters are working to “move toward finding out exactly what happened, when, and hopefully—one day—who did it,” said Maria Pevchikh, head of investigations for Mr. Navalny’s anticorruption fund.