The deceased, identified as Shilpa Agarwal, used to operate a 'sahayak kendra' of a nationalised bank from her house at Mejia in Bankura district, the police said.
The arrested man, Rajiv Kumar was the manager of the same branch, the police said.
Agarwal had told her family that she was going to visit her aunt's house at Asansol in West Burdwan district on Friday.
Police said they had received a complaint about stench emanating from the trolley bag kept in the store area of the apartment. On opening the bag, they found Agarwal's decomposed body, cut into pieces.
Her family alleged that Kumar had committed the crime as Agarwal had been demanding that he return the Rupees one lakh which he had taken from her.
Police said investigations were on.