The bodies of Cory Breton, 28, and Iuliana Triscaru, 31, were found in a large metal toolbox near Brisbane. 19120474/ AAP

Cook Islands criminals may choose to be deported here, says Immigration.

A Cook Islands-born mother of seven will likely be deported home after serving her jail time in Australia for the manslaughter of a couple tortured and locked in a metal box.

Ngatokoona Mareiti, 40, did not have a hand in the murders, AAP reports. But she admitted helping clean a Brisbane unit as Cory Breton, 28, and Iuliana Triscaru, 31, were tied up, and while they screamed from inside the metal toolbox.

The court heard Mareiti first spotted the pair sitting on a couch with their hands tied behind their back in the hours before they died but did nothing about it. She heard them screaming from inside the toolbox at a home she visited to buy drugs before it was thrown into the water, prosecutor David Meredith said.

Mareiti also purchased cleaning products under the direction of one of her co- accused and helped clean the unit where the couple had been detained.

Later, she helped dump the dead man's car, then lied to the dead woman's family in the days after the murder, telling them not to worry.

“They’d obviously been assaulted and interrogated by ther other accused. She would have noticed Breton was bleeding from the mouth,” Meredith said.

Cook Islands Principal Immigration Officer Kairangi Samuela says any country can deport a person to their country of citizenship should they commit deportable offences.

Cook Islanders hold New Zealand citizenship so they are deported to New Zealand or, if they choose, to Cook Islands. There is no legal obligation for one government to inform the other that a person is being deported, but this is usually done as a common courtesy.

“The deportee may well be given an option if he advises that he is a Cook Islander or family advise Corrections in Australia that the person is a Cook Islander and choose to come here rather than New Zealand.”

Mareiti was initially charged for double murder but she pleaded guilty to two counts of the lesser charge of manslaughter, which the Crown accepted. She was jailed for nine years but, with time served, will be eligible for parole in June.

In sentencing, Justice David Boddice said the victims Cory Breton and Iuliana Triscaru died horrible deaths and that Mareiti assisted her co-accused when she “knew that the unlawful killing was a probable consequence”.

He accepted she was not involved in their initial detention, physical assault and “the dreadful way they were dealt with, which led to their deaths”.

“Your involvement was, however, significant,” he concluded. “It was apparent from the fact they were tied up right from the start that this was a dreadful event.

“You did nothing about contacting the authorities. You did nothing about attempting to encourage the others to desist from their conduct.

“By your dreadful and, what I consider, despicable deeds, you allowed events to unfold that caused the deaths of these two people.”

The court heard Mareiti was friends with the victim Triscaru, and their children played together.

A victim impact statement from Triscaru’s mother called Mareiti a coward, evil and a liar who had destroyed her family.

“You left her there to be tortured and to be killed,” she said. “You have turned my life into a forever nightmare.

“If you had called the police perhaps she would have been alive today.”

Justice Boddice, addressing Mareiti as tears welled in her eyes, said: “The decisions you made showed a complete lack of human decency.”

Mareiti is to be deported upon her release.

Seven others are awaiting trial for that charge after the two bodies were found so badly decomposed investigators were unable to determine if they died from drowning or suffocation, the Brisbane Supreme Court heard on Tuesday.