A Russian court on Thursday found opposition leader Alexei Navalny guilty of embezzlement and sentenced him to five years in prison.
Navalny was accused of embezzling $500,000 worth of timber from a state-owned company, while working as an adviser to a provincial governor in 2009.
The opposition leader, who has exposed alleged government corruption, says the charges are politically motivated and are intended to silence him.
Navalny had recently registered to run for Moscow's September mayoral race.
Under Russian law, he is not eligible to run for mayor or any future office due to his conviction.
Earlier this year, Novaya Gazeta, an opposition newspaper researched the rulings of Judge Sergey Blinov who heard Navalny's case. All his verdicts were "guilty" in 130 rulings in an 18-month time period.
Navalny has said he wants to become Russia's next president and jail current President Vladimir Putin and his associates.
Last year, Navalny angered Mr. Putin by leading mass street demonstrations in Russia's capital.
The Wall Street Journal has described Navalny as "the man Vladimir Putin fears the most."
Navalny helped organize mass protests starting in 2011 against alleged electoral fraud and Mr. Putin's return to the presidency.
Navalny's anti-corruption blog has drawn as many as a million views from Russia's Internet savvy younger generation.