After driving between the five addresses the two men finally found the woman with her ex-husband.
The woman's ex-husband could smell alcohol on both men and said that the officer immediately started threatening the woman.
Both say they heard the off-duty officer say, "I am going to smash your face in", before he grabbed her and pulled her down by the hair.
She recalled curling herself into a ball after she hit the ground, raising her arms to protect her face and lifting her knees to protect her torso.
"I was punched multiple times in the back of my head," she said.
"As well as multiple times into my right ribs, back of my neck and lower back where my kidneys are.
"It felt like it was a frenzied attack."
Her ex-husband tried to intervene but was placed in a headlock by the ex-partner.
The four struggled and ended up on the grass next to the raised patio.
She was reportedly crying at the end of the fight, and her hoodie and bra had been torn.
On the other hand, the officer claimed the woman had been drinking and was agitated by his arrival, calling him "a corrupt cop".
He claimed she launched herself at him.
"She caught me by surprise by running at me screaming with her hands outstretched. I was standing perhaps 3m away, if not more.
"I reacted by grabbing [her] by the hair and pushing or pulling her head in a downwards motion as she collided into me.
"Her hair was the only part of her I had the opportunity to grab as her hands were already past mine."
At 11.45pm, the woman called 111 to say she had been assaulted.
Later on November 5, 2015, the woman dropped off her torn clothing at Papanui Police Station as evidence.
On November 20, the officer declined to answer questions in relation to the assault saying, "I'm the victim here".
Following a criminal investigation, police found there was insufficient evidence to prosecute any person involved in the confrontation.
The IPCA ruled there were deficiencies in this investigation and that there were potential lines of inquiry that police should have followed up.
However, the IPCA was satisfied the subsequent Code of Conduct investigation into his actions was carried out thoroughly and impartially.
IPCA general manager Warren Young said the off-duty officer's actions showed poor judgment.
"He should have waited for on-duty officers to arrive rather than involving himself in a physical confrontation."
Once he became involved in that confrontation, he used excessive and unjustified force against the woman, Young said.
Canterbury Metro Area Commander Superintendent Lane Todd said police accepted the findings of the report that an off-duty officer used excessive force during the dispute.
"The police officer involved in this matter was given a disciplinary sanction," Todd said.
"Police have since provided conflict of interest training to all of our teams to ensure greater awareness and mitigation strategies."
