Police have confirmed the body found in Manurewa over the weekend belongs to a 16-year-old girl.
Her body was discovered off McVilly Rd about 4.30pm on Saturday.
The girl's family have asked police not to release her name and are seeking an interim suppression from the coroner's office.
"Her family are understandably devastated by her death and are struggling to come to terms with what has occurred," Detective Senior Sergeant Mike Hayward, Counties Manukau Police, said.
"Our community will in no doubt be shocked by the young age of the victim in this investigation."
Hayward said investigators were continuing to analyse CCTV footage and make inquiries in the wider area, but they could not comment on every specific aspect of its Operation Casting homicide investigation.
"Our priority is the integrity of the case and releasing too much information at this stage could jeopardise that," he explained.
"However, we would like to reassure our community that our detectives are working hard and are piecing together what has led to this girl’s death."
Anyone with information is asked to contact 105, quoting the file number 210911/6094.
People can also call Crimestoppers anonymously on 0800 555 111.