Police in Brahmanpara, Cumilla, detained three people after Md Abul Bashar, a 50-year-old day laborer, died following an alleged beating on the night of 4 August.
Family members and eyewitnesses said the incident took place in Uttarpara, Nalla village, Dulalpur union, after three members of Bashar's daughter's in-laws arrived to invite the family to a ceremony marking the fifth month of his pregnant daughter Myna Akter's pregnancy.
Relatives said Bashar declined because a nephew's wedding was scheduled the same day, which led to an argument.
According to the family's complaint, his daughter's father-in-law Abdul Motin choked him and punched his chest, while Rozina Begum and Md Hriday also beat him.
Bashar was taken to Brahmanpara Upazila Health Complex, where the duty doctor declared him dead.
Brahmanpara police station officer-in-charge Md Faruk Hossain said the body was sent for autopsy to Cumilla Medical College Hospital's morgue, an investigation was underway, and the victim's family was preparing to file a case.
Bashar's wife Jhorna Begum alleged that their daughter had been tortured over dowry demands since marriage and that a long-running dispute existed between the two families.