Detective Senior Sergeant Paul Wilson said the woman has been in custody since her last court appearance on November 20.
Family shouted messages of support to her during her first appearance last month, while someone in the public gallery called her a “monster”.
Wilson said a second person — a 61-year-old woman — was also arrested following this morning’s search warrant. She faces charges of manslaughter, assaulting a child and assault with a weapon.
Both women are due to appear in the Whakatāne District Court tomorrow.
“As the matter is now before the courts, police can not provide any further comment,” Wilson said.
Family members have posted tributes online to the young boy, who also went by the nickname Joppy.
“Mummie and Daddy love you. Forever 8, my son.”