Two days later, wildlife enforcers stopped Hahn in his campervan, where they found four jewelled geckos, each placed in a sock which was tied and inside a plastic container.
Today at Christchurch District Court he pleaded guilty to charges of hunting and possessing the geckos, which he claimed he intended to swap for gila monsters, which he collected.
In sentencing him to 16 weeks imprisonment, Judge Raoul Neave told Hahn that New Zealand's unique, indigenous and rare wildlife needed protection.
"You came here with the express purpose of catching these geckos and taking them," he said.
"Crimes like this increase the risk of such animals becoming extinct."
But Judge Neave accepted that Hahn - who has a collection of four lizards back in Germany - was more of a "mad collector" than a "cynical commercial poacher".
He told him he was a "misguided, naive, and hopelessly over-enthusiastic lover of wildlife" who had been "stupid in the extreme".
DOC prosecutor Mike Bodie told the court that the four jewelled geckos were unharmed and had been released into the wild.
But he said that such crimes were on the rise, with seven foreign nationals now having been caught coming to New Zealand to poach protected wildlife.
Mr Bodie said it was "heart-breaking" as DOC could only stop a "portion of those coming here to do that".
Defence counsel Peter Maciaszek said his client was ashamed of trying to expand his lizard collection by illegal means and deeply regretted what he did.
Judge Neave urged legislators to consider increasing the maximum penalties for such crimes under the Wildlife Act, which currently stand at six months' imprisonment or a $100,000 fine.
Conservation Minister Kate Wilkinson welcomed the conviction.
"The actions of this man are appalling and a gross insult to all New Zealanders,'' she said in a statement.
"Jewelled geckos are found only in New Zealand and are worth more to us than any price they would fetch on the illegal market. Even removing a few of these treasures could have a devastating impact on their population.''
Ms Wilkinson said she was working on a Bill that would double the maximum penalty to $200,000 and lift the maximum jail term to three years. This stronger penalty regime also means convicted smugglers would not be able to return to New Zealand for 10 years.
"I want to send a clear message to would-be smugglers that our native species are off limits and that they are not welcome back in our country.''
"I've also asked DOC to continue working with the international community to make it tougher for smugglers to get our geckos, and other animals, into countries that do not have trade restrictions on endangered species.''
