CBI special magistrate Krishna Kumar ordered her to be lodged in the high-security Beur jail after she was produced before him this morning.
The court also remanded Navlesh Pathak, a journalist also arrested in connection with the case, to judicial custody by another 10 days.
CBI had on April 2 filed a charge sheet against Rupam Pathak in the court under section 304 (culpable homicide not amounting to murder).
CBI sources said further investigation into the case would continue.
Pathak had stabbed to death Kesari at his house at Purnia on January 4, 2011. His supporters caught her and beat her mercilessly before handing her over to the police.
Chief Minister Nitish Kumar had on January 8 recommended CBI probe into the case following a written request by Deputy Chief Minister Sushil Kumar Modi.