A Chinese student was kidnapped after his flatmate pulled out of a blind date with a woman he met on the internet and sent him in his place.
The woman was in fact being used as bait in a kidnapping plot.
Three people were last week found guilty of kidnapping Yang Liu in March 2004, while a fourth is already in prison awaiting sentencing.
The young student was held for a ransom of $1 million.
Police say the four, Peng Fei Huang, Bo Xiang Zhang, Yang Shi, and Bing Cao wanted the money to pay debts to their friends.
Senior Sergeant Kevin Brennan said Liu's flatmate had met Shi in an internet chatroom. The plan was to lure him to the North Shore for a date.
But a one-way plane ticket back to China booked the day before he was supposed to meet her saved him, and he sent Liu in his place.
"The flatmate misses out on getting kidnapped and [Liu] gets it instead."
When Liu turned up for his date, he was tied up by his captors and bundled into the boot of his own car while Zhang drove off in the vehicle the four had arrived in.
Liu's family in China alerted police when they got the ransom demand, and a fax was sent to Auckland police.
Tracked phone calls and Eftpos transactions led to the capture.
Liu was a prisoner for 48 hours - he was bound, blindfolded and beaten, and given nothing to eat but a duck leg.
He was released and given $300 by his captors after his mother wired $60,000 to New Zealand and it was collected by the four, one posing as Liu.
Police tracked Liu's Eftpos card and found Zhang's friends, who said they were meeting him at 1am the following day in Newmarket to get a further $2000 he owed them, which they needed for visa applications.
A plainclothes Chinese officer went with them and Zhang was arrested.
When police arrested them on April 5, Shi and Cao were booked on a one way flight to China at 6am the following morning.
The four were eventually released on bail with home detention bracelets which have cost their families $800 a month for the past two years.
Police say Zhang was an overstayer with a gambling habit. His visa had run out about 12 months before the kidnapping. Cao's had also run out. He had been living off his girlfriend Shi.
Police say Huang was the only one of the four who appeared to have money. He had gambled $120,000 at Sky City within a year.
Police said the plotters had "obviously watched a bit of CSI".
They wore latex or woollen gloves and cleaned every surface, Mr Brennan said.
"They even wiped his car."
The case has revealed the cheating of some foreign students to get into the country. Witnesses said it was common practice among international students to lend money to their friends to help them fulfil student visa requirements.
Students taking courses of more than 36 weeks must provide evidence of $10,000 in their bank accounts.
The four will be sentenced in September.