A 13-year-old allegedly mentally ill boy had attacked his grandmother with a sharp weapon, Police said.
The 81-year-old victim had later succumbed to severe injuries. Police investigations had revealed that the attack was carried out due to a dispute over breakfast.
The deceased was a resident of Talgaspitiya, Aranayake.
The boy had been arrested by the Hemmathagama Police and further investigations are being conducted into the murder.