Surviving Siberia's toughest prisons: The bleak conditions faced by some of Russia's worst offenders... and how one criminal got through five years inside
Boris Kovalyov, 32, spent five and a half years in high security prisons in Siberia for drug-trafficking
He was given early release from his eight year sentence for good behavior
Boris Kovalyov may only be 32 but he has spent most of his adult life serving in some of Russia's toughest prisons.
Within months of being released early from a sentence for theft at a prison camp near the Siberian city of Krasnoyarsk, he was sent back for drug-trafficking.
There he endured one of the hardest penal regimes in the world.
Daily chores: Inmate Boris Kovalyov, 32, was sentenced to eight years in a high-security prison camp for drug trafficking.