Moscow (AFP) -
A Russian court on Tuesday sentenced a respected Gulag historian, Yury Dmitriyev, to 13 years in prison on a controversial child sex charge.
Dmitriyev is known for his work for the prominent rights group Memorial, locating the mass graves of victims of Stalin's terror.
The 64-year-old has faced a series of trials on related charges, at which he has pleaded not guilty.
Supporters insist he is being targeted because of his work exposing the horrors of the Soviet era.
He was initially arrested in 2016 and charged with child pornography over several nude photos of his adopted daughter that he said he took to monitor her growth. A court acquitted him in 2018.
This not-guilty verdict was later overturned by a higher court and he was put back on trial on a new charge of forced sexual acts involving a child.
He was sentenced to 3.5 years in jail in July this year, most of which he had already spent in pre-trial detention.
Prosecutors appealed against the verdict, asking for a harsher sentence, while Dmitriyev also filed an appeal asking for all charges to be lifted.
As a result, the supreme court of the northwestern Karelia region on Tuesday issued a new, far harsher sentence that cancels the previous one.
'Dmitriyev has been found guilty of committing the crime with a punishment of 13 years of imprisonment in a harsh-regime penal colony,' it said.
- 'Politically motivated' -
He still faces hearings on two other charges.
'It's obvious that this verdict was not based on law, that this verdict is politically motivated,' a senior Memorial member, Oleg Orlov, told the Echo of Moscow radio station.
'Memorial and the defence will fight against this sentence,' he added, with an appeal to a higher Russian court and a complaint to the European Court of Human Rights.
'The Karelian Supreme Court?s decision to prolong historian Yuri Dmitriyev's already unjust sentence by an outrageous 10 additional years is another step backwards for #humanrights and historical truths in #Russia,' tweeted Rebecca Ross, spokeswoman for the US embassy in Moscow.
Dmitriyev spent decades locating and exhuming mass graves of people killed under Joseph Stalin's rule, including in the notorious Gulag network of forced labour camps, and set up a memorial to them in Karelia.
The Memorial rights group declared Dmitriyev a political prisoner and said the real reason for his prosecution appeared to be 'his activity in preserving the memory of political repressions'.
Memorial investigates Soviet-era persecution of political prisoners and also campaigns against present-day rights abuses.
Russian authorities have cracked down on the organisation and labelled it a 'foreign agent.'