A foreign gang member convicted of New Zealand's biggest heroin-trafficking operation was allowed to stay in the country because of confusion over his immigration status, and has gone on to rack up a dozen more criminal offences.

Sam A Lam, 42, should have been deported after he was convicted of importing $70 million of heroin from Thailand in 1998. He was sentenced to a 13-year prison term for trafficking 10kg of near-pure heroin, hidden in a piece of art.

Customs officials double-checked because the art work looked so cheap.

But no other country would take him and so he was allowed to stay on in New Zealand.

As a refugee who fled Vietnam as a child, he no longer has Vietnam travel papers. And the United States wouldn't take him because he wasn't a citizen, even though he went there as a refugee.

Since his release from prison, Lam has been found guilty of nearly a dozen charges including four drink-drive offences, theft, careless driving and three incidents of driving without a licence this year.

He is to appear in Taupo District Court on November 28 for driving while disqualified.

When the Herald on Sunday visited him at his Pakuranga home on Friday, Lam said: "So you guys interested now, eh? How did you get the story? Nobody know about this."

He said his co-accused, Hui Au Wong, the alleged kingpin in the operation, was dead.

When asked how he had died, Lam laughed.

Lam said he wanted to return to Vietnam but was unable to.

"They want to take me back, that's where I'm born, but I can't."

Lam came to New Zealand just a week before he was arrested in 1998. Prior to coming to New Zealand he was living in Oakland, California, where he was connected to the triad gang.

"He was 'muscle', brought over to add a bit of clout to the operation," said one police officer familiar with the case.

"He is known in the Asian criminal community in New Zealand," said another source.

Lam, who bears gang tattoos on his arms, is living in Pakuranga and working as a painter-decorator.

Peter Elms, intelligence general manager for the Department of Labour, said Lam did not hold documentation that would allow his return to Vietnam.