The woman had mental health issues and her death, believed to be a suicide, followed Serco officers searching her room, he said.
"They hadn't seen her distressed immediately after the search but they realised that she had mental health problems and people had argued she really shouldn't be in there.
"She needed help and that help just wasn't available inside the detention centre. Not surprisingly, many people's mental health problems are made worse by detention."
Rintoul said it was believed the woman was in her late 20s or early 30s and had been detained under section 501 of the Migration Act for about six months.
The woman's death had followed an "epidemic of suicides" New Zealand's Prime Minister Jacinda Ardern should now seize on, he said.
"I'm really hopeful that this latest suicide will be one more reason for the Ardern Government in New Zealand to act with a greater sort of vigour.
"Now that there's a Labor government in Australia, there really should be some greater connection which says the Section 501 deportation of New Zealand citizens has to stop."
Ardern has congratulated Australia's new Labor Prime Minister Anthony Albanese on his win and said she was looking forward to formally meeting him soon.
Rintoul said Australia's Labor party had promised to review any exceptions or provisions for discretion process regarding New Zealand 501 deportees.
"Under the legislation at the moment if people are sentenced for a crime of 12 months or longer their visas are automatically cancelled.
"That means a lot of people are caught by drug offences and repeat traffic offences. The vast majority of people who are sent back to New Zealand are sent back for drug offences; they're not 'Mr Bigs' of the drug industry at all."
Rintoul said the Australian government was already being investigated over the suicide of an Iranian refugee in 2019 and he wanted to see a "full investigation" into this latest death.
RNZ has contacted the New Zealand Government for comment.
Where to get help:
• Lifeline: 0800
543 354 (available 24/7)
• target='_blank'>Suicide Crisis Helpline: 0508 828 865 (0508 TAUTOKO)
(available 24/7)
• Youthline:
0800 376 633 or text 234 (available 24/7)
• target='_blank'>Kidsline: 0800 543 754 (available 24/7)
• Whatsup: 0800 942
8787 (12pm to 11pm)
• Depression
helpline: 0800 111 757 or text 4202 (available 24/7)
• Anxiety
helpline: 0800 269 4389 (0800 ANXIETY) (available 24/7)
• Rainbow Youth: (09)
376 4155
If it is an emergency and you feel like you or someone else is at risk, call 111.
