Four months after someone threatened to poison infant formula with 1080, the police say they are no closer to finding whoever made the threat.
A blackmailer warned they would carry out the threat today unless the practice of dropping the pest poison in the bush was stopped.
The police launched an investigation last November after Federated Farmers and Fonterra received anonymous letters accompanied by packages of milk powder laced with 1080.
The scare made international headlines, due to its potential impact on the multi-billion diary industry.
Police deputy commissioner Mike Clement said they had spoken to hundreds of people in their investigation but might never find the culprit.
"Today it's as complex as it was on day one. It's one of those things that there's a massive amount of information to sort through and I don't know whether we will get a successful conclusion.
"But what I can say is that we are committed, have been from the outset and will remain committed as long as there are avenues of inquiry to follow and that the public are helping us with those inquiries," he said.
The Ministry for Primary Industries said people should feel confident that infant formula was as safe today as it was before the threat.
It said it had a range of measures in place including a new 1080 testing programme and strengthened security in retail stores.
Deputy director-general Scott Gallacher said he was confident products were safe.
"Ever since we found out about this threat, we have been working with manufacturers and retailers and everyone in the supply chain to make sure we have every confidence as to the safety and integrity of products on the shelves today or being exported," he said.
Supermarkets remain viligant
Both major supermarket chains said they have not relaxed their vigilance over infant formula products.
They said they retained the extra safety measures put in place after a threat was made to lace the products with 1080 poison.
The managing director of Foodstuffs Steve Anderson said there was continuous CCTV monitoring of shelves, a staff member keeping a watch on the shelves and clear signage informing the public of the threat.
Countdown said it was protecting products from the time they arrived in the distribution centres to when they were purchased.
Meanwhile, infant formula exporters said exports had not been affected by the threat.
Infant Formula Exporters' Association chair Michael Barnett said the threat had not diminished demand.
"Initially I think there were some stalls at the border and you would expect as the systems got in place for checking and monitoring, but that's been removed.
"As far as we're concerned anyway, the supply chain is flowing as normal at the moment."
Mr Barnett said the global market was confident New Zealand production plants were safe.