Police recovered the body of a worker in a sack in Chaugachha upazila of Jashore district on Friday morning.
The deceased was identified as Bipul, 45, a resident of Swarupdah union in the upazila.
Liton said Sabuj of the same village and his brother-in-law called Bipul out of the house on Wednesday for buying a cow.
But, he did not return home later.
Local sources said Bipul had an extra-marital affair with Sabuj's mother. He might have been killed over the relation.
Passers-by saw the sack beside a road in Bergobindapur area this morning and informed police.
Being informed, police went there and found a body inside the sack and, later, the deceased younger brother Liton Mia identified it as the body of Bipul, said Chaugachha Police Station officer in-charge (OC) Rifat Khan Rajib.
The body was sent to Jashore 250-bed Sadar Hospital morgue, he added.