The victim was identified as Hosne Ara Begum, 60, wife of Abdur Rahim.
Quoting relatives of the deceased, police said Abdur Rahim, a retired engineer of Public Works Department, along with his wife had long been living in the house as their three sons live in different places for their job purposes.
On March 18, Abdur Rahim went to Saudi Arabia for performing Umrah, leaving Hosne Ara alone at the house.
On Thursday, the elder son of the deceased made repeated phone calls to his mother. As his calls went unanswered, he requested his aunt, Jharna, to go to their house.
When Jharna went to the house around 9 pm, she found Hosne Ara lying on her bed in a pool of blood while the doors and almirah of the house open.
She later informed police about it who recovered the body and sent it to Sadar Hospital for autopsy.
Pankaj Chandra Roy, superintendent of Bagerhat police, said the motive behind the murder is not clear.