Kanat Mukhambetkaliev, 23, was brought to the maximum-security Kushmurun prison in Qostanai Oblast on September 28 and died at a hospital on October 6. An official autopsy cited kidney failure as the cause of death.
Vadim Kuramshin, who monitors human rights in Kazakh penal facilities, told RFE/RL that there were numerous bruises on Mukhambetkaliev's body that might have been caused by beating.
The Coalition of NGOs Against Torture said it has copies of the autopsy documents. It said it wants to participate in the investigation it has called for.
Earlier this month, former Kushmurun prison Director Aleksandr Sadovsky and two of his former associates were found guilty of taking bribes and sentenced to prison terms.
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