A Russian court has increased a jail sentence for the Gulag historian Yury Dmitriyev to a total of 15 years on charges his supporters say are punishment for his work exposing Stalin-era crimes. Supporters say Dmitriyev, 65, is being targeted because of his efforts to expose the horrors of the Soviet era under Joseph Stalin. Dmitriyev is also the local head of Memorial, the country’s most prominent rights group, which may be shut down by the courts this week. Last year, a court in north-west Russia sentenced Dmitriyev to 13 years in prison on a controversial child sexual abuse charge. In December, prosecutors requested that the sentence be extended by two years. On Monday, a court in the city of Petrozavodsk extended the historian’s sentence at the prosecutors’ request. “Fifteen years to Yury Dmitriyev,” Memorial tweeted. Dmitriyev spent decades locating and exhuming mass graves of people killed under Stalin’s rule and set up a memorial to them in the Karelia region of the north-west of Russia. In recent years he has faced a series of trials on a number of charges including sexually abusing his adopted daughter. He has pleaded not guilty. He was initially arrested in 2016 and charged with possessing child sexual abuse images over several nude photos of his adopted daughter that he said he took to monitor her growth. A court acquitted him in 2018. In a surprising turnaround, the not-guilty verdict was later overturned by a higher court and Dmitriyev was put back on trial on a new charge of forced sexual acts involving a child. He was sentenced to three and a half years in jail in July 2020, most of which he had already spent in pretrial detention. Prosecutors appealed against the verdict, asking for a harsher sentence. As a result, the supreme court in Karelia issued a new sentence in September 2020, sending him to a high-security penal colony for 13 years. Memorial rights group has declared Dmitriyev a political prisoner and says the real reason for his prosecution appears to be “his activity in preserving the memory of political repressions”. Memorial, which investigates Soviet-era persecution of political prisoners and also campaigns against present-day rights abuses, says it could be shut by the year’s end.