Russian lawyer Sergei Magnitsky, who died in 2009, has been found posthumously guilty of tax fraud by a Moscow court.
Sergei Magnitsky was arrested in 2008 after accusing officials of tax fraud, but was later himself accused of the crime.
His death in custody a year later led to a major diplomatic dispute between Russia and the United States.
In the same trial, William Browder, CEO of Hermitage Capital Management which Sergei Magnitsky represented, was also found guilty of tax fraud.
William Browder was convicted in absentia, and sentenced to nine years.
The London-based hedge fund manager has denied the charges and said the trial was politically motivated. His defense team have said they will appeal against the verdict.
In a statement, he said the verdict “will go down in history as one of the most shameful moments for Russia since the days of Joseph Stalin”.
“The desperation behind this move shows the lengths that Putin is ready to go and to retaliate against anyone who expose the stealing and corruption he presides over,” he said.
No sentence will be passed for Sergei Magnitsky, whose relatives regard the case as illegal.
A lawyer for the family told Russia’s Rapsi news agency: “I did not doubt that the decision would look like this.”
“I know that he committed no crimes.”
It is believed to be the first time in Soviet or Russian history that a defendant was tried posthumously.
Employed as an auditor for Hermitage, Sergei Magnitsky uncovered what he described as a web of corruption involving Russian tax officials, including the alleged theft of more than $200 million.
After reporting the allegations to the authorities, he was himself detained on suspicion of helping Hermitage evade $17.4 million in taxes.
Sergei Magnitsky was accused of having registered two firms in the republic of Kalmykia – at the time a Russian “offshore” tax haven – to hide assets.
Then, it is alleged, he hired local people with disabilities as “analysts”, entitling the firms to tax benefits. In his pre-trial testimony, Sergei Magnitsky insisted that the firms’ tax advantages were legal and that those hired were genuine, wage-earning employees.
He had pancreatitis and died in custody in 2009, but an investigation by Russia’s presidential council on human rights concluded that he had been severely beaten and denied medical treatment.
Last December, a Russian court acquitted a prison doctor accused of negligence over Sergei Magnitsky’s death. And in March this year the investigation into his death was dropped altogether due to “lack of evidence of a crime”.
William Browder has described the charges filed against him as an “absurdity” and revenge for his campaign to put pressure on Russia over the Magnitsky case.
He said it was his expectation “that no Western country will co-operate with the Russians”, as Interpol has said it considers the trial politically motivated.
“We will carry on in our fight for justice for Sergei Magnitsky as long as it takes,” William Browder said.
The case became a symbol in the US of the fight against corruption in Russia.
Last year, Washington passed the Magnitsky Act, blacklisting Russian officials accused of human rights violations, including those linked to the case.
In response, Russian President Vladimir Putin signed a law barring Americans from adopting Russian orphans.
The Russian foreign ministry also drew up its own blacklist of US officials who are alleged to have committed human rights violations.