Joshna Bibi was arrested for killing Abdul Rakib Molla with a sharp weapon when he was sleeping inside a room of their house at Pachpara Road of Rajabagan in Garden Reach area, they said.
"The incident probably took place after midnight when the woman attacked the boy in his sleep, injuring him. The boy was rushed to SSKM hospital but was declared dead on arrival," an officer of Kolkata Police Detective Department said.
According to the police, the accused was suffering from mental depression which might have led to the incident. She was arrested and the weapon used in the attack has been seized.