The public servant who handled the citizenship application of a millionaire Chinese businessman with multiple identities was told by his boss to "stop asking questions", a transcript of court evidence shows.
The Serious Fraud Office last night said it might yet make its own inquiry into how William Yan - also known as Yang Liu and Yong Ming Yan - was granted citizenship.
Mr Yan was this week acquitted of immigration fraud charges, but questions remain over why Labour MP Shane Jones, when a Cabinet minister, granted him citizenship against official advice.
Labour leader David Shearer has stood down Mr Jones from the front bench, but said the MP would be reinstated if the Auditor-General found he acted properly.
Mr Jones granted Mr Yan citizenship in 2008 against the advice of officials, who said there were questions about whether he met good-character requirements because he had two passports with two names and two birth dates, and was wanted in China for an alleged large-scale fraud.
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.
"He was so anxious that we send the files to the minister. He just wanted the file to go to the minister," said Johannes Gambo, an Internal Affairs case officer in Auckland.
Mr Gambo wanted to make further inquiries with immigration authorities in Australia.
"I had a phone call that I was told not to ask any more questions because there was a lot of political pressure to send the file to Wellington.
"I was told to just process the file, send it to Wellington, don't worry about asking any more questions.
"I have been working there for seven years and that was the first time I have had my boss phone me about an application."
Asked who called him, Mr Gambo named the general manager of citizenship, Geoff May.
Mr Gambo said he told Mr Yan at a meeting in May 2008 that it was unlikely he would get citizenship because there were so many unresolved issues.
"He said to me, 'I'm confident it will be okay. I've got a lot of support from the MPs'."
In cross-examination, defence lawyer David Jones, QC, suggested to Mr Gambo that he was lying and said there was no documentation of his conversation with Mr Yan.
Mr Gambo denied he was lying and another Internal Affairs citizenship officer, Judith Broad, was later called to give evidence.
She recalled Mr Gambo telling her and other staff members that Mr Yan was confident of getting citizenship despite the questions over his application.
"He came back into the back office and said, 'Mr Liu is very confident he is going to get citizenship because he has got lots of backing and support from MPs'," said Ms Broad.
She described this as "shocking".
Justice Timothy Brewer this week found Mr Yan not guilty of four charges relating to false declarations on immigration papers in 2001 and 2002 and one of using false written statements to get citizenship.
"In this case ... I have concluded that the most the Crown can achieve is a high level of suspicion, but that is not enough," the judge said.
Shane Jones has previously said he granted Mr Yan citizenship on humanitarian grounds because an Internal Affairs official told him Mr Yan risked execution if he returned to China.
Yesterday, an Internal Affairs spokesman said the files on the case had now been checked and there was no record of a departmental official discussing that issue with Mr Jones.
"We are not saying absolutely that didn't happen, but we don't have any [record of it]."
Serious Fraud Office director Adam Feeley said the SFO had approached the Auditor-General to signal interest in the case.
"If they raise any concerns coming out of their inquiry, we will deal with them."
- Additional reporting: David Fisher, Claire Trevett