Russian investigators on Tuesday dropped their investigation into the 2009 death in jail of a whistleblowing attorney whose case led to a crisis in relations between Russia and the United States.
The investigators said they had no evidence that Sergei Magnitsky died at the age of 37 from beatings by prison staff, as his family and US-born former employer William Browder claim.
"Based on the preliminary investigation's results, a decision was taken to end the criminal case due to a lack of evidence of a crime," the Investigative Committee said in a statement.
Magnitsky is currently facing a posthumous trial -- Russia's first -- along with Browder into alleged tax evasion.
The Russian lawyer was jailed shortly after disclosing an alleged $230-million fraud scheme being run by senior tax and law enforcement authorities and accused of carrying out the fraud himself.
An attorney for Magnitsky's mother Natalia said he intended to appeal the decision in court.
Magnitsky's prosecution by the very same officials he had singled out for fraud has come to symbolise the Kremlin's failure to crack down on corruption and institute the rule of law as repeatedly promised by President Vladimir Putin.
Browder had hired Magnitsky as an accountant for his Hermitage Capital hedge fund -- the single largest foreign investor in Russia at its height nearly a decade ago.
Magnitsky then discovered an alleged scheme under which officials received fraudulent tax refunds for the funds paid by Hermitage Capital to the state.
He was arrested and investigated for tax fraud only months thereafter by those very same officials.
Magnitsky died less than a year after being remanded in custody without ever facing trial.
Russian officials attributed his death to chronic ailments that failed to receive proper treatment in detention and opened a probe into medical negligence. No one has been convicted of mistreating the lawyer.
Browder -- now a British citizen and based in London -- has made it his mission to get Western governments to impose sanctions against Russians implicated in the case.
The United States responded late last year by barring the entry and freezing the bank accounts of dozens of Russians who were believed to have abused Magnitsky's rights.
Russia responded with fury by imposing its own blacklist against US officials and halting adoptions by American families.
The tit-for-tat sanctions saw relations between the two superpowers sink to one of their lowest points during former KGB agent Putin's 13-year rule.
Browder is now lobbying the European Union to adopt similar sanctions against Russia to those imposed by the United States.
The Russians for their part have opened posthumous hearings into the tax fraud allegations against Magnitsky.
His family has boycotted the Moscow trial and refused to send lawyers to hearings that have been repeatedly postponed as a result.
But proceedings were finally launched earlier this month when the state appointed a public defendant to represent Magnitsky and Browder before the judge.
The next hearings have been scheduled for Friday.