Four members of a family, including two children, were killed at a farmhouse in Bandarban on Thursday night.
Md Amin, 45, his son Junayed, 12, sister Samira Begum, 30, and her son Syed Nur, 4, died as their throats had been slit.
Amin worked at the farmhouse located at Kamlang area in Kuhalang union and police said the four had been living there for long.
It was not clear who killed them but Imtiaz Ahmed, officer-in-charge of Bandarban Sadar police station, said family rows could be a motive for the murders.
Amin had a longstanding dispute with his first wife and police said they were searching for her as her involvement was suspected in the crime.
The four were described by police as suspected Rohingya nationals who came to Bangladesh from Myanmar illegally.
The bodies were sent to Bandarban Sadar Hospital morgue for autopsy.