Moscow. A Russian court has handed down a guilty verdict for whistleblower lawyer Sergei Magnitsky, whose death in detention led to one of the biggest Washington-Moscow rows in years.The court on Thursday also found Magnitsky’s onetime client, the US-born British investor William Browder, guilty of evading about $17m in taxes.Al Jazeera’s Peter Sharp, reporting from Moscow, said that this was the first time a Russian or Soviet court had brought about a prosecution against a dead man.Browder’s sentence is expected to be announced later but the case against Magnitsky ends with his verdict as the authorities cannot take a case against a dead man any further.The tax evasion case against Magnitsky, who died in pre-trial detention after accusing interior ministry officials of corruption, has been slammed by legal experts and Western governments.Magnitsky died in custody in 2009 at the age of 37 after attempting to reveal massive tax fraud against the British Investment Fund Hermitage Capital, to which he was an adviser before, and the Russian state.He had accused interior ministry officials of organising a $235m tax scam, but was then charged with the very crimes he claimed to have uncovered.He was placed under pre-trial detention in 2008 and died of untreated illnesses less than a year later, just days before the expiry of the one-year limit that he could be held without trial.Human rights groups claim he was beaten in prison. According to his diary entries, Magnitsky was abused, tortured and held in squalid conditions.Browder, who is now based in London, insists Magnitsky was tortured to death with beatings and the refusal of proper medical care.The Kremlin’s own human rights council admitted he had not received the proper medical treatment.Prison doctor Dimitri Kratov, who is also the deputy head of the jail, was accused of denying Sergei urgently needed medical aid, leading to his death.But in May, state prosecutors dropped all charges against Kratov and he was allowed to walk free.The United States earlier this year passed the “Sergei Magnitsky Act” which imposed a visa ban and froze the assets of 18 officials implicated in the lawyer’s death.The legislation infuriated Moscow, which in retaliation passed legislation prohibiting Americans from adopting Russian children.