Ms Fan's file history showed she first came to New Zealand in 2009 on a visitor's visa and was later granted a working visa and finally permanent residence, on the basis she was Preston's partner.
The pair met over the internet in 2003 when Preston was teaching English in China. They married in 2006, lived together and had two children together.
The four lived as a family in New Zealand from 2011 and she was granted residency in August 2012.
But the marriage was soon over.
"Preston was requesting for [Immigration NZ] to deport Fan for providing false information and for being a burden to the New Zealand economy," Ms Go said of his complaint.
She contacted Preston and he passed to her a file he said backed up his claims, including what he said was evidence she was with another man, Tani Hoyhtya, during the period she said she was in an exclusive relationship with Preston.
Ms Go said dates of birth Ms Fan provided in documentation were consistent and she had declared past health problems.
There was though evidence to suggest Ms Fan was having a relationship with another man while living with Preston, including social media chat messages that said: "I will not move out until I get PR [permanent residency]."
There was also a hotel booking for Ms Fan and Mr Hoyhtya in Auckland in early 2012.
Ms Go recommended the case be allocated to an immigration investigator.
Preston included Ms Go in further emails in September and October 2013, which were also sent to Government ministers and other officials.
These emails asked how Ms Fan could afford various expenses, such as a car, when she was on the unemployment benefit.
Family friend Merryn Toomey then told the court Preston became obsessed with Ms Fan after they split.
"[He was] furious really. He wanted her gone. He contacted a lot of official agencies trying to stop her obtaining a benefit and trying to get her passport taken away and trying to get her removed from the country," Ms Toomey said.
The trial continues.
