The girl whose body was found at a vacant house in south Auckland was in the care of Oranga Tamariki when she was killed.
Demetrius Pairama, 17, was found on July 8 in Māngere but police believed she died the day before.
- Government axes 'vulnerable' from Ministry for Vulnerable Children
- Former CYF runaways back with whānau
- Oranga Tamariki apologises after posting child's details on Trade Me
Her whanau were told of her death on July 9, her mother Lena "Blue" Hetaraka-Pairama said.
"I broke down and couldn't stop screaming," she said.
Police told her Demetrius was unrecognisable and they had to use her finger prints to identify her. The funeral home managed to fill in parts of her face so she could have an open-casket funeral.
A cause of death hasn't been released yet.
Demetrius had only been in Auckland for about a year after being brought up by relatives in Northland, Ms Hetaraka-Pairama said.
But she got sick of the rules and started running away to see boys.
"The second time she ran away, which was just before Christmas, she didn't want to come back and then she was out in Manurewa with a boy and [Oranga Tamariki] got involved."
Demetrius was in state care when she died, Oranga Tamariki confirmed in a statement to Newshub.
"Our thoughts are with her family and friends," it said.
"As the matter is before the courts, we are unable to comment further."
Ms Hetaraka-Pairama said her daughter had ADHD, schizophrenia and the mental age of a 10-year-old.
"She was not silly, she was really clever but she was mentally challenged."
The police have charged a 28-year-old woman and a 24-year-old man for Demetrius' murder and have not ruled out further arrests.
Newshub.
