This is reported by the Investigative Directorate of the Investigative Committee for the Irkutsk Region.
"In Bratsk, a criminal case has been initiated into the death of a minor girl," the agency's website says.
According to the investigation, the unconscious girl was taken to the hospital in Bratsk on December 4, and until December 19 she was in a coma.
Despite the resuscitation measures, the girl died.
Investigators interrogate medical staff and hospital officials.
Earlier in the Moscow region, a woman was detained on suspicion of strangling a ten-month-old child while walking.