A man facing serious drugs charges escaped his jury trial because he was mistakenly deported by authorities.
Jianzong Bai was meant to go on trial at the Auckland District Court on a charge of possessing methamphetamine and three charges of importing pseudoephedrine, a precursor of methamphetamine.
But instead, Bai was deported back to China after having served a home detention sentence for other drugs charges.
Customs deputy controller of operations Bill Perry said a review of just how Bai was able to avoid his trial was underway.
"We'd obviously prefer that it hadn't happened ... We invest a lot of time and effort in identifying these people and placing them before the courts so when an administrative process like this breaks down, it is of concern to us."
Mr Perry said Bai served a home detention sentence for drug offending and, at the end of the sentence, Immigration deported him.
He said that happened because authorities didn't link both sets of offending to the same man.
Mr Perry said Bai spelled his first name - Jianzong - with a "z" but the first offences were recorded with an "s" replacing the "z" - Jiansong.
Mr Perry said Bai's birthdate was also recorded differently - exactly a month out.
He said authorities were looking into whether Bai did this on purpose or whether it was just an administrative botch-up.
Mr Perry said it was unlikely that Bai would face a trial on the charges after he was returned to China.
He said Customs hadn't been in touch with authorities in China and it was unlikely Bai would return to New Zealand.
Customs was investigating how this happened, he said, and would talk to everyone involved in the case.
The process will take about a month.
Mr Perry said, while there hadn't been cutbacks in Customs' prosecution and investigation unit, there had been a growth in the number of cases and more and more drugs were being seized as they come into the country.
He was adamant that New Zealanders could still have confidence in Customs.