A man accused of killing his partner and her daughter told undercover officers the woman had become aggressive and threatening before he killed her.
Kamal Gyanendra Reddy, 42, is charged with the murder of Pakeeza Yusuf and her 3-year-old daughter Juwairiyah "Jojo" Kalim.
The Crown alleges the pair, whose bodies were found under the Takapuna overbridge in October 2014, were killed at the end of 2006 or start of 2007.
After a six-month undercover police operation, which began in April 2014, Reddy sat down with an officer and was repeatedly asked to disclose any significant secrets he may have.
He eventually confessed to killing the two victims and unwittingly guided officers to where he said he had buried the bodies.
Reddy even posed up for a photo under the bridge, which was taken by the undercover cop who had spent the preceding months gaining his trust.
Afterwards, the defendant explained Ms Yusuf had been demanding money from him despite him having paid nearly $3000 to move her and her daughter to a Howick rental property.
In covertly-recorded conversations played for the jury today, Reddy described her behaviour as "too much aggressive".
He said when his mother came over from Fiji, Ms Yusuf started "playing up".
"She changed," he said.
After an incident at a family gathering, Reddy told the undercover officer, their relationship spiraled out of control.
Ms Yusuf allegedly threatened to call the police on the defendant and told him not to come back to the house.
"Was it just after she created that scene that you decided to get rid of her?" the officer asked.
"Game over," Reddy said.
He described her as "a pretty lady" but believed she had met someone else just before the alleged murder.
Last week, two interviews, which were covertly filmed on October 14, 2014, were played for the jury at the High Court in Auckland.
Prompted by a series of questions in the second sit-down, Reddy told an undercover officer he strangled Ms Yusuf with the cord of an electric iron while she was in bed.
"She's gone and then after, I go for the daughter," he said.
"So I just got rid of her ... and take her body and dump it where the new bridge was making on the North Shore."
He earlier told officers he had smothered Jojo with a pillow and afterwards disposed of items including the iron and pillow case.
Thinking he was speaking to a friend rather than a covert operative, Reddy told the officer he had put the corpses in his car and driven to the Bombay Hills, south of Auckland, to dispose of them.
When he could not find an appropriate spot, he allegedly opted to bury them in Takapuna under a motorway bridge that was under construction.
When asked how he knew Ms Yusuf was dead, Reddy said her arms and legs had gone "tight".
The court has heard how an undercover officer gained the defendant's trust through a series of "simulated criminal scenarios" before he made the admissions.
But at the trial's opening, defence lawyer Jonathan Krebs warned the jury to be skeptical of the so-called confession.
"I say to you from the outset: it's false, it's a cobbled-together story."
He said his client was effectively groomed by undercover officers to the point where there was "immense pressure" on the 42-year-old to make admissions.
"What if a person didn't commit the crime but knew enough about the crime to give a plausible narrative?" he said.
The trial continues.