The girl's body was found hanging from the ceiling fan in her hostel room in Sahabganj locality yesterday, Deputy Superintendent of Police Om Vir Singh said.
Singh said prima facie it was a case of suicide but the exact cause of the death could be ascertained after post-mortem.
Roli was studying in Class II at the residential school run by the government social welfare department.
Reports said her father Satya Ketu had visited the school yesterday to bring back his daughter home on leave. He later left telling his daughter to get the leave sanctioned by the hostel superintendent. However, later on the girl was found dead in the hostel room.