"The ability of someone to be deported, change identity, and be back quickly is a concern," acknowledges Alistair Murray, who manages investigations and compliance for Immigration New Zealand.
"Because we don't know who is here."
Investigators then took a closer look at the suspected immigration fraudsters to build profiles of the individuals.
Two common factors were discovered. First, they were from Malaysia.
The sort of work which Murray's staff had already identified as a risk for unlawful migrant labour, alongside the horticulture and hospitality industries.
A target list of 10 companies to be investigated had already been drawn up.
So the pieces of the puzzle fell into place when the identity fraudsters, picked up by accident, were linked to the companies hiring unlawful workers.
The dovetailing of evidence led to Operation Spectrum, the most successful investigation ever into the hidden workforce in New Zealand.
Industry chiefs have urged for new technology or building techniques to be picked up locally, in order to lift productivity.
Others are searching for staff overseas.
Beijing-based developer Fu Wah wants short-term visas for 200 Chinese workers to complete the $200 million Park Hyatt hotel on Auckland's waterfront.
But in the meantime, the overheated demand for tradesmen means an illegal workforce bas been able to flourish in the Auckland construction scene.
Shoddy workmanship was uncovered in Operation Spectrum. But Alistair Murray is quick to point out no one is in danger of a building collapsing.
"We're talking about painting, tiling, gib-stopping...it's finishing work," says Murray, "rather than compromising the structural integrity of the walls or anything like that."
Nor was it a case of exploitation of the workers. Though some were paid as little as $20 an hour, most received $35 or $40 an hour.
A legitimate tiler might be $60 or $70 an hour, says Murray.
"So Kiwis are being cut out of jobs. Legitimate Kiwi businesses trying to contract in that market can't compete with those rates. It's not a level playing field.
"Then there's an obvious tension because you've got building companies who need to get the work done and they can't find enough people."
Developers and site managers wouldn't know if someone was allowed to work in New Zealand, says Murray, as most unlawful workers were employed by third-tier subcontractors.
The goals of Operation Spectrum were two-fold. To disrupt the illegal labour supply and gather evidence to prosecute anyone who gained New Zealand residency through fraud.
Arriving unannounced at large construction sites around Auckland, often with more than 200 people working there, presented unique challenges.
And they weren't always successful; Murray recounts an incident when at least 20 illegal tradies scattered through the streets of Mt Wellington. "They just scarpered, disappeared when we turned up.
"Even on the most simple of sites, it was a massive exercise to do a floor-by-floor sweep with two people blocking each exit. We'd find people hiding in fire exits, stairwells, ceiling cavities," says Murray.
"Or sometimes they were in the middle of plastering a wall and we'd tap them on the shoulder to say: 'You've been here unlawfully for 10 years, time to go home'."
When rounded up by Operation Spectrum, the illegal workers told similar stories.
Most had responded to advertisements posted on social media, or recruited by a "facilitator" in Malaysia, offering work in New Zealand.
Some of the recruiters had been deported, changed their names, then returned to New Zealand.
On entering the country, they would get a temporary driver's licence. This would be used as the identification to register a company and open a bank account.
These were essentially "shell companies", says Murray, and staff were paid in cash.
"It was common to hear 'we got paid every Thursday by a man in a black Audi'," says Murray.
"We are talking significant cashflow, hundreds of thousands of dollars. Of all the people we deported, not one paid tax."
New Zealand has a reciprocal tax agreement with Malaysia but a spokesman said Inland Revenue was unable to comment on "ongoing investigation work".
But from the perspective of Immigration New Zealand, the final results of the six-month Operation Spectrum can be hailed as a success.
A total of 54 individuals were deported back to Malaysia, including directors of the 10 companies.
A further 36 people voluntarily left New Zealand when they realised the net was closing and 15 Malaysians who had visas to live in New Zealand, but not to work, were served with deportation liability notices. Just three have appealed.
On average, those 105 people had each lived in New Zealand unlawfully for five years. One had been here for two decades.
Investigators developed an algorithm to profile visitors likely to join illegal construction crews and 85 were stopped at the New Zealand border, or sometimes even before they set foot on the plane to carry them here.
In total, 190 people have been stopped from illegally working here. Of those, 15 were previously deported from New Zealand - or left voluntarily - but returned under a new identity.
Just two went on to obtain permanent residency; the rest have been deported, or fled, for a second time. And this week one of them faced the possibility of spending time in a New Zealand prison.
'Deliberate plan to deceive'
Adam Gan Bin Abdullah hides his face when appearing in the Manukau District Court. Photo / Doug Sherring
Adam Gan Bin Abdullah stood in the dock and cried, hiding his face from the camera.
On Monday, the 39-year-old builder was in the Manukau District Court to be sentenced on eight charges of immigration fraud.
Abdullah used to be called Meng Kuang Gan, his name when he first came to New Zealand in 2008.
He lived here lawfully for two years, but was deported in 2012 - and banned from New Zealand for five years - for failing to obtain the correct working visa.
On his return to Malaysia, Gan married a Muslim woman and, as is the legal custom in Malaysia, took her surname.
He legally changed his name to Adam Bin Gan Abdullah and received a new passport.
Less than a year after being deported, Abdullah was back in New Zealand.
He presented his new passport and completed the arrival card - failing to declare his previous deportation.
Over the next four years, Abdullah was granted numerous visas in New Zealand and was eventually given permanent residency.
On each and every application, he omitted the details of his previous identity and deportation.
On one occasion, Abdullah went further, stating he was working as a builder in Malaysia in the years he was actually living in New Zealand as Meng Kuang Gan.
When he was finally identified by Operation Spectrum and charged, Abdullah's attitude was one of entitlement. He claimed he did not intend to manipulate the system.
"I have no doubt you knew exactly what you were doing," Judge John Bergseng told him this week.
"You failed to disclose that information, because if you did, you would have failed to gain entry to New Zealand."
Immigration New Zealand pushed for a prison sentence, while Abdullah's lawyer Michael Kan asked for home detention.
"He did not intend to hurt anyone in New Zealand, just to get a better life" says Kan. "He cheated the system, now he is paying the price."
In advocating for home detention, Kan said his client would struggle in prison surrounded by "hardened criminals" and anticipated Abdullah would be stripped of his residency.
"He will be deported, never to come back to New Zealand again," said Kan, although doing so was exactly why Abdullah was in trouble in the first place.
Judge Bergseng decided by a "fine margin" to sentence Abdullah to 10 months' home detention at an address in Flat Bush.
"Truthful declarations are the cornerstone of the New Zealand immigration system. Your offending directly challenged this," Judge Bergseng said.
"You had a deliberate plan to deceive. This was clearly premeditated, fraudulent and repeated. Having been successful once, you thought you'd get away with it again."
Alistair Murray has declined to comment on the sentence. But he is confident Abdullah - and anyone else who is deported - will now be stopped from coming back into the country.
He says facial recognition software at Auckland International Airport is constantly improving, while Immigration New Zealand collects - and checks with other countries - biometric data of anyone deported each year.
There's also a dedicated team which checks details provided by visa applicants to an existing database of information, which picked up 88 dual identities in 2017.
"As well as vigilant people in our visa services office spotting photographs," says Murray with a smile.
Adam Gan Bin Abdullah pleaded guilty to eight immigration charges. Photo / Doug Sherring
Operation Spectrum
• 54 deported • 36 voluntarily left NZ • 15 served deportation notices (no work visa) • 85 stopped at border • 190 people stopped from illegally working in NZ • 0 tax paid
