Russian investigators say that an official of a labor camp in the city of Engels in the Volga region has admitted beating a prisoner to death.
Penitentiary inmate Artyom Sotnikov, 25, was found dead in solitary confinement in April.
The official, who was earlier questioned as a witness in the case, turned himself in to investigators.
The Federal Investigative Committee said five officials had been charged in connection with the incident.
Beatings and torture of inmates in detention centers and penitentiaries have come under scrutiny in Russia after police tortured a suspect to death in the Tatarstan region in March.
The incident caused a public outcry.
The Investigative Committee and Interior Ministry have launched probes into similar alleged incidents across the country.
Based on reporting by Vzsar.ru and Interfax