Eventually, the group decided that 13 investigators from the police, Immigration, Customs, IRD and Internal Affairs would search the Metropolis apartments and cars.
"The number of staff reflected the size of the residential area to be searched - five units in a hotel and three vehicles," according to documents released by Immigration New Zealand.
However, "no documents were seized and/or evidence retained as a result of the search warrant."
Mr Yan later complained, through his lawyer, that customs officials stepped outside the authority of the warrant by taking photographs inside the apartment.
The raid happened at the same time as Labour MP David Cunliffe, the Immigration Minister at the time, was considering an application from officials to have Mr Yan's residency revoked.
The grounds for revocation were that he had failed to disclose the Yong Min Yang identity, the fact that he was married in Australia and was wanted by the Chinese authorities on an alleged fraud.
Mr Cunliffe declined to revoke his residency and asked officials to continue investigating the potential immigration fraud.
The following year, Mr Yan was granted New Zealand citizenship by Labour Party minister Shane Jones against the advice of officials that he did not meet the good character test, because he had two passports with two names and two birthdates, and was wanted in China for an alleged large-scale fraud.
He was later charged with immigration fraud but was acquitted this year after a High Court trial in Auckland. Justice Timothy Brewer ruled that he was not guilty of false statements on immigration and citizenship papers.
During the High Court trial, a Department of Internal Affairs official said Mr Yan was confident of gaining citizenship because of support from MPs such as Labour's Dover Samuels.
Mr Samuels, a friend of Mr Yan and former Maori Affairs Minister, wrote several letters in support of his citizenship bid and was in court at the acquittal.
Other links to the Labour Party emerged during the trial, including the fact that fundraiser Shane Te Pou filled out the citizenship form for Mr Yan and introduced him to Rick Barker, the Minister of Internal Affairs at the time.
Mr Te Pou is also the brother of Daniel Phillips, who was Mr Jones' private secretary.
The ministerial decision on citizenship was shifted from Mr Barker to Mr Jones because of a "real or perceived conflict of interest".
Mr Jones has previously said he granted citizenship on humanitarian grounds because Mr Yan risked execution if he returned to China.
That decision is now going under the microscope of the Auditor-General, Lyn Provost.
The terms of reference for the inquiry include probing how and why Mr Jones gave Mr Yan citizenship. The inquiry will also look into the policies and practices of Internal Affairs when advising its minister on citizenship applications, especially when there are questions of good character.
