An FIR has been registered against the accused Abdul Sattar (40), a resident of Kashmiri Gate locality in Ramgarh.
According to a complaint filed by the victim's mother, the accused was found raping the girl last night, Additional Superintendent of Police, Rakesh Pandey said.
The victim also told the police that she was being sexually exploited by her step father for over a year, Pandey added.
A manhunt has been launched to nab the accused, who is absconding.