Razia Sultana Kakoli, a 42-year-old widow, and her 8-year-old son Talha Islam were found dead with their throats slashed on Sunday, according to Araihazar Police Station chief Azizul Haque.
After her husband's death, Razia and her son had been living in the upazila's Gopindi area.
The two of them had gone to bed the previous night without any incident but in the morning, neighbours found the front door of the house wide open with broken locks, according to Azizul.
"The CID's forensic unit is combing the house for evidence. An investigation is underway to unravel the mystery behind the murders."