Two people have now been charged with the murder of Rotorua toddler Nia Glassie and another two with her manslaughter.
Three-year-old Nia died in Auckland's Starship Hospital on August 3 from injuries allegedly inflicted at her Rotorua home.
Sergeant Mark Loper said after lengthy discussion with the crownMichael William Curtis, 21, and Wiremu Curtis, 17, were now facing murder charges.
Michael Paul Pearson, 19, and Oriwa Terrina Kemp, 17, were now charged with manslaughter.
All four, who had been previously been jointly charged with assaulting Nia in July this year, would appear in Rotorua District Court tomorrow.
Mr Loper said the charges were upgraded after police received a pathologist's report, which confirmed Nia died as a result of a brain bleed.
Police were also looking at charging Nia's mother, 34-year-old Lisa Kuka, over her role in the abuse, he said.
Police had told Ms Kuka about the pathologist's report and questioned her again on her knowledge of the circumstances around Nia's death and the accompanied abuse, he said.
A decision over whether she would face charges would be made in consultation with the crown in the next two to three weeks.
A fifth man William Curtis, 47, is facing separate counts of assault and injuring Nia with intent to cause grievous bodily harm over a prior four-month period, from March 1 to July 1.
The charges against him have not changed.
Among allegations already published are that the little girl was spun in a clothes drier, hung from a washing line, left on the roof of a house and used for wrestling practice.
Curtis Snr allegedly wrapped a scarf around the toddler's neck and, holding both ends of it, lifted her off the ground.
