An eight-year-old schoolboy found dead in his bed died from asphyxiation, tests show.
Gardai are waiting to question the mother of Anthony Ward, who remains in hospital receiving medical care.
Tributes have been paid to the youngster, who was described as a lovely, kind and friendly boy by the principal of the school he was due to go back to on Monday.
Psychological support will be offered to his young friends, as health chiefs review their involvement with the family prior to the "tragic incident".
Carmel Walmsley, principal of Shandrum National School in Newtownshandrum, said the board of management, staff and pupils are deeply saddened at the death of Anthony.
"Our sympathy and thoughts are with Anthony's family and friends," she said.
"Anthony was a lovely boy, kind and friendly, and will be greatly missed by all who knew him."
Anthony's mother Diane Ward, 43, remains in the care of Cork University Hospital after being found in a distressed state by her son's side in the bedroom of the family home in Harrison Place, Charleville, Co Cork.
Gardai investigating the death of the eight-year-old later arrested a woman in her 40s.
"She is detained at Mallow Garda Station under Section 4 of the Criminal Justice Act 1984 and can be held for up to 24 hours," a spokesman added.