Oranga Tamariki was first made aware of Nevaeh Ager over a year and a half before her murder by her drug-fuelled father, while the family were living in Hawke's Bay.

The two-year-old was found dead in Bay of Plenty, on March 21, 2019.

Her father Aaron Izett pleaded not guilty to murder by reason of insanity, but was convicted after a High Court jury trial in Rotorua in November, 2020.

According to internal documents released by Oranga Tamariki, Ager first came to their attention in July 2017, when her family was living in Hawke's Bay.

On July 18 that year, police made a report of concern to OT regarding an incident at the family home 10 days earlier while Ager was present.

The report states that Izett appeared to be "highly intoxicated on meth and was not making much sense", but co-operated and left the address.

Social workers later visited the home on July 27 and discussed a "safety plan" with mother Alyson Ager.

Under the report heading "how safe in Nevaeh in the home", the staff noted that no further action was necessary.

"No current harm, family actively pursuing safety and child responding to this," the report states.

In February 2019, an anonymous report was made to OT where a caller stated Izett is a "nutter" and raised concerns there may be drug dealing/manufacturing within the home.

Following further contact with the family in October that year after another incident, the last time concerns were raised about Ager was just three days prior to her murder.

Alyson Ager had given birth to another child on March 18, 2019 – she and the baby were discharged from the hospital on the same day Neveah's body was found.

Police have apologised for their lack of action to protect Ager, having wrongly told her great-grandparents, who had called 111 when Izett attacked them the day before the murder, that nothing could be done.

Aaron Izett pleaded not guilty to murder, but was convicted after a High Court jury trial in Rotorua in November, 2020. (Photo / Andrew Warner)

The report states that police received numerous calls in relation to a naked man running about the Pukehina estuary area on the day of the murder.

The man, assumed to be having a psychotic episode, was tasered by police and sedated by ambulance staff with ketamine. Three hours later the body of Neveah Ager was found.

After Izett assaulted his daughter, he placed her naked body face-down in water on mudflats and placed two large rocks on top of her.

Pathologist Rexson Tse gave evidence that Nevaeh sustained multiple bruises and abrasions to almost all her body, caused by a weapon or weapons.

He said there could've been 70 to 80 blows to her body, including at least 10 or possibly up to 20 to the toddler's head, and a torn ligament in her neck.

Crown prosecutor Kieran Raftery QC told the jury at the trial that Izett's violent assault was "brutal in the extreme".

Raftery said Ager would have suffered a "severe reign of terror" and the force used "spoke volumes" about his intention to kill her.

Izett will be sentenced on February 3, 2021.

An Oranga Tamariki spokeswoman said the death of any child is a "tragic and traumatic event".

"Should a child die while in the care of custody of Oranga Tamariki, we investigate the circumstances fully to understand what happened and whether anything could have been done to prevent it, in order to ensure that potential risks are identified in future cases," she said.