Hazaribagh police station officer-in-charge (OC) Ahad Ali told Prothom Alo that the two sisters lived in the flat with their mother and a brother. His brother was outside the flat while his mother was ill.
The OC quoted family members as saying that the sisters were mentally ill. He was undergoing treatment.
There is a suspicion that one of them may have committed suicide after killing the other, but nothing can be said before the investigation is completed, the OC said.
DMCH sources said that the bodies have been kept in the mortuary.