Magnitsky, a lawyer who, by some accounts, discovered a $230 million fraud by police and tax officials, was arrested and charged with the fraud himself. He died in a Moscow prison in 2009, reportedly after a severe beating, though President Vladimir Putin had publicly said Magnitsky died of heart failure.
Magnitsky's employer, investment manager William Browder, was also convicted Thursday, in absentia. Now in London, Browder was sentenced to nine years in prison, though his attorneys say they will appeal.
"Today’s verdict will go down in history as one of the most shameful moments for Russia since the days of Joseph Stalin," Browder said in a statement. "This is the first conviction of a dead man in Europe in the last ten centuries."
A decade ago, Browder was a strong supporter in Russian President Vladimir Putin, and invested in the country through his firm Hermitage Capital. But Browder pushed for more transparent corporate governance, making him a target.
Corporate documents were stolen from Hermitage, to be used in the tax fraud Magnitsky later uncovered.
"Doing business in Russia means either you've effectively become part of a criminal regime or a victim of a criminal regime," Browder told The Guardian following the verdict.
"There's no way to do business in Russia without seriously compromising yourself or putting yourself in grave danger," he said.
Outrage over his case led to The Magnitsky Act, a piece of U.S. legislation imposing financial and visa sanctions on corrupt Russian officials, and Russia retaliated by banning Americans from adopting Russian children. Britain reportedly informally banned officials associated with the Magnitsky case as well.
"When the Putin regime ultimately falls, future generations of Russians will be naming streets and monuments after Sergei Magnitsky for his heroism and sacrifice," Browder said. He said the case "shows the lengths that Putin is ready to go to to retaliate against anyone who exposes the stealing and corruption he presides over."