Police would now look to interview the suspect, victim and witnesses.
"We will request through the New Zealand Police Commissioner's Office for support with this phase of the investigation as it will be done in New Zealand," Tetava said.
NZ Police said they were assisting Cooks Islands Police. "The results of those inquiries will be provided to the Cook Islands Police in due course. Police are not able to comment further at this stage."
Fraser earlier told the Herald she had been randomly targeted by two men and two women just before midnight at the popular Rehab nightclub in Avarua.
"As I was walking through the bar, there were four people - two were females, two were male," she said.
"A female said to me: 'Keep walking'. I stopped and said: 'What? What do you mean keep walking?'
"She said: 'Straight up, keep f***ing walking'. I literally flipped her a blank look. I said: 'I'm literally walking, what do you mean?'"
The woman then allegedly splashed her drink at Fraser, before she and three others rushed towards her and immediately began punching and kneeing her about the head.
Fraser stayed standing, bending down to cover her face and head as much as she could because she felt the beating would be worse for her if she fell to the ground.
"I kept thinking: 'Don't get knocked out, do not get knocked out'. I thought it would stop, but it just got worse.
After the attack, a friend ran outside where police had attended an earlier fight.
A uniformed female officer spoke to Fraser and her friends but saidshe did not understand them.
Fraser was due to be on a flight back to New Zealand at 2.30am and decided to get a ride back to her hotel, pack and head to the airport.
"They tried to gouge my eyeballs out. Their fingers were so deep in my eye, I actually had to pick their fingers out.
"That's when I started thinking: 'Oh wow, you really need to get out of this'. They had such a good grip on my dreadlocks that I couldn't get away."
Asked what she thought may have provoked them, Fraser said they may have been involved in an earlier altercation outside and she had simply been in the wrong place at the wrong time.
"I didn't want to stay there so I didn't even tell the people there what had happened because I didn't want to be stuck there. I just wanted to go home.
"I didn't realise my jaw was broken, either, until we got here."
As a result, a formal complaint was not made to local authorities.
However, Cook Islands Police began investigating after members of the Fraser family posted photos of their relative's injuries on social media, calling for those responsible to come forward.
Tetava also took aim at members of the public and the "erroneous and slanted reporting by the Cook Islands News" for what he said was false accusations that an off-duty police officer had been involved in the attack.
"We can confirm that the off-duty police officer was not involved. In fact, none of the three men accused through a Facebook-posted photo, as well as a fourth person, were involved in the assault on the victim," he said.
"The errors in reporting and gossip on Facebook needed to be put right."
