At least 100 migrants, six properties and several companies are now at the centre of a complex Immigration New Zealand (INZ) probe.
The development follows a Newshub investigation that uncovered dozens of men crammed into filthy, run-down properties in south Auckland.
Some had no food and hadn't received the hours or salary promised, despite paying overseas agents tens of thousands of dollars for job offers.
INZ has now provided an early insight into the major investigation, revealing it involved a total of 115 Indian and Bangladeshi nationals living in "overcrowded and unsanitary" conditions across six Auckland homes.
Some of the men on Sunday night called the police upon their food running out, forcing them to turn to begging. Newshub visited the Papakura property and found dozens of migrants crowding the street.
The migrants arrived via the accredited employer work visa scheme.
In its statement, INZ said investigators had begun talking with the migrants involved.
"Given this is a complex active investigation it will take time to gather all of the evidence. There are restrictions on what details can be shared publicly in order to not potentially jeopardise the outcomes of the investigation or any subsequent prosecutions.
"Our investigators have spoken with 115 Indian and Bangladeshi nationals who arrived in New Zealand on accredited employment work visas (AEWV) with the promise of employment when they arrived. Individuals have indicated they paid a substantial amount for the visa and a job, yet most are still waiting for any paid work."
The men were housed in properties "not fit" for so many people, INZ said.
It said some of the men had been in New Zealand for several months, while others had only recently arrived.
"Investigations into the employers who brought the individuals to New Zealand continue but we can advise that there are several people and companies of interest pertaining to this case.
"Our first priority was to ensure the health and wellbeing of all these individuals which included ensuring each property had food, water, electricity as well as connecting them with local agencies who can provide pastoral care and support."
Indian migrant Prasad Babu said on Sunday they'd gone three days without anything to eat.
"You guys took $20,000 from us to get a job," he told Newshub.
"Why did you promise us you can give [us] a better life here? There is no better life here."
INZ said investigators would now speak with multiple witnesses and continue gathering evidence.
"The Indian High Commission has been engaged to provide support to their nationals," the statement said.
"INZ is working to contact offshore visa holders who are linked to this case to notify them not to travel until they receive further contact."