Documents released by Immigration NZ show Yang claimed - and produced documentation to support the claims - he spent the period 1978-1993 studying and working at Luoyang University.
The Financial Times broke news last month Yang had actually studied as an undergraduate at the People's Liberation Army Air Force Engineering Academy, and later lectured at elite spy school the Luoyang Foreign Languages Institute.
The Foreign Languages Institute is reported to be part of China's military intelligence apparatus, training linguists to intercept foreign communications. Yang's immigration file shows his areas of focus at the Foreign Language Institute were the English language and American studies.
In a press conference shortly after the story broke, Yang said he listed this institution at the request of unspecified Chinese authorities.
"When I left China I was asked by the system to use my partnership universities ... It is not that I am deliberately trying to cover-up. It's because the system asked me to use the partner university. That is the reason."
Yang denied he was a spy, but conceded he could be seen as having taught spies.
Newsroom noted Luoyang University was only founded in 1980, making claims to have studied there prior to this date difficult to sustain.
Questions to Yang about exactly who asked him to be vague about his work and study history, and to what end, and why official certificates were prepared supporting this claim, have gone unanswered.
Did Yang have access to sensitive materials?
The protection of sensitive government information is largely tasked to the Security Intelligence Service - who are also reported to have investigated Yang in 2016 - through a process of security screening and vetting.
Sources familiar with government classification and security vetting processes were unanimous in telling the Herald that Yang's past would likely preclude him being cleared to view sensitive documents.
"There's no way in the world Jian would have got security clearance," one said.
Another noted: "Given his past it would take a very long time, if he got it at all."
The New Zealand SIS are said to be "extraordinarily rigid" in its approach to foreign citizenship, to the extent that marrying a foreign national - or even being born in a friendly country such as Australia - raises significant hurdles for anyone attempting to secure clearance.
Another source said Yang's background - and closeness to New Zealand's PRC embassy - was well-known in senior Wellington circles and had led to self-censorship. "I'm sure everyone is aware of that, and would be careful about what they say in his presence," the source said
The vetting process, however, does not apply to MPs. There are obvious dangers to democracy in allowing spy agencies to dictate who can and can't be a Member of Parliament.
This convention has raised concerns among those spoken to by the Herald about the extent to which Yang had access to information he would likely have been denied if he were a public servant required to undergo security screening.
Yang played an unusually prominent role for a backbench MP when accompanying former Prime Minister John Key on formal visits to China in 2013 and 2016.
In the more recent trip Yang is pictured seated at the top table - alongside Key and the Ministers for trade and primary industries - in meetings at Beijing's Great Hall of the People opposite a Chinese delegation including Xi Jinping, the powerful General Secretary of the Communist Party of China.
In the earlier trip Yang boasted in a video blog of being in attendance when Key met Chinese premier Li Keqiang. "I was there, and I witnessed the meting. Very, very exciting," Yang said.
Diplomatic sources raised concerns about the level of involvement Yang had in these high-level meetings, as well as likely access to the formal briefing document prepared for John Key ahead of the trip outlining New Zealand and China's position on likely topics of discussion.
"Would Jian have seen the briefing papers that were given to John Key? Almost certainly. He sat up the front of the aircraft with the Prime Minister and his advisers - I can't imagine for a moment he didn't have access to it."
The source said this briefing document - unlikely to include top-secret classed intelligence from the Five Eyes network - would have been given a classification of confidential or higher.
Questions over the past fortnight from the Herald to the Prime Minister's office about these matters have gone unanswered.
Why the official silence?
The response from Parliament to the affair as been curiously muted, and the timing of the governments' response to inquiries can be seen at best as convenient, and at worst cynical.
Requests to the Department of Internal Affairs to release Yang's citizenship saw documents released on the eve of election - but with the crucial section detailing what exactly Yang had disclosed of his past work and study in China completely redacted. Following protests these redactions were lifted, but only after Yang had been returned to Parliament.
Immigration New Zealand, in response to multiple requests to release what Yang had disclosed when applying for residency in 1998, first delayed its response then choose to release the information late on the afternoon on October 19. This timing saw files showing Yang listed Luoyang University in his application made public two hours before Winston Peters' much-anticipated press conference announcing who he would from a government with.
Both Internal Affairs and Immigration NZ have said the revelations about Yang's background and apparent lack of disclosure were not grounds to review their handling of the matter. A spokesman Immigration NZ went as far as to say "no new information has come to light which would warrant an investigation", despite the facts being novel enough to warrant front-page coverage last month in the London-based Financial Times.
The lack of political oxygen to address the saga can be partly explained by the all-consuming election campaign, but also there are suggestions our two largest parties have made self-interest and national interest calculations in declining to address questions over Yang.
National and Labour have both put closer engagement with China at the centre of their foreign affairs platform. The last Labour government inked our world-leading free trade deal with the regional superpower, and National followed in further deepening economic ties.
A recent paper by University of Canterbury academic Anne-Marie Brady on the extent of China's influence in New Zealand noted both parties counted China-born MPs with cozy relationships with the local embassy in their caucus.
No matter the discomfort over the questions, the New Zealand public deserves answers.
