"I remember being told - I won't name the person - 'You know he became a citizen?'
"I didn't think there was anything exceptional about it. I'd only become aware of it after I left politics. Certainly, the way it was spoken to me, it wasn't said to be an unusual thing," he said.
Mapp said he was aware of one citizenship approval where living-in-New Zealand requirements were waived.
"That was where a person wanted accelerated citizenship to represent new Zealand in sports," he said.
Mapp said Thiel was a welcome addition to New Zealand, and recounted a meeting with him in 2010, in his capacity as Minister of Research Science, and Technology.
"He seemed really engaging and really interested in New Zealand."
This support for Thiel was matched by the Prime Minister, who said during a press conference in Christchurch the venture capitalist had been "demonstrated his commitment" the country after being granted permanent residency 2006 by made sizable charitable donations and business investments.
"I don't think there's anything suspicious here at all. New Zealand is a better place with Mr Thiel as a citizen," he said.
Thiel's citizenship was approved under an "exceptional circumstances" clause of the Citizenships Act by the then-Internal Affairs Minister Nathan Guy in 2011.
His sole statement on the issue said: "I don't recall this specific application".
"As minister I tended to follow the advice of DIA officials on these issues; I'm advised officials recommended granting citizenship in this particular case," he said.
Guy has declined multiple requests to discuss Thiel.
Current Minister of Internal Affairs Peter Dunne claimed the first he'd heard of Thiel was following the Herald's reporting late Tuesday of his citizenship.
The New York Times has covered the revelation, contrasting Thiel's foreign citizenship with his support for the nationalist presidential campaign of Donald Trump, and said:
"The news that one of the richest citizens of New Zealand is a naturalised American who was born in Germany set off an immediate furore in the island nation, with questions being raised about whether being a billionaire gets you special treatment."
The limited response from New Zealand authorities - beyond confirming Thiel was approved for citizenship on June 30, 2011 the Department of Internal Affairs has declined to answer questions about the affair - has failed to satisfy opposition MPs.
Labour Party immigration spokesman Iain Lees-Galloway said the reasons behind the decision needed to be made public:
"We now know that Nathan Guy did grant citizenship under exceptional circumstances, but is refusing to front up and explain what these exceptional circumstances were. This raises yet more questions that must be answered."
The section of the Citizenship Act used in the Thiel case said ministers must determine if it is in the public interest to waiving of usual requirements for citizenship - such as living in New Zealand for most of the past five years, or being born to native parents.
"Why did the minister believe that granting New Zealand citizenship to Mr Thiel was be in the public interest because of exceptional circumstances of a humanitarian or other nature," Galloway asked.
"New Zealanders deserve answers."
