A mother and her two children died mysteriously at Peerbaria village in Brahmanbaria yesterday.
The dead are Nargis Akter, 35, her daughter Tarin, 8, and son Safi, 6.
Narigis's husband Selim Mia is missing, said police.
Police said neighbours, after finding the house silent and locked, alerted police. Police rushed to the house and found the bodies with seemingly no mark on them.
Brahmanbaria Sadar Hospital carried out the autopsies and samples of tissues were sent to a hospital in the capital for tests, said hospital sources.
Md Abdur Rab, officer-in-charge of Brahmanbaria Sadar Police Station, said they took all clothes and food from the house to find out how they died.