Yixin Gan is an Auckland mother of three accused of arranging for 250kg of drugs to be smuggled into New Zealand.

She has pleaded not guilty but the Crown say she found the "almost perfect" method. This is how it allegedly happened.

1) Gan and her husband Fei Lin export food from China to Tonga via New Zealand. The shipping container is unloaded at the Port of Auckland and transferred to Auckland International Airport.

READ MORE: The 'almost perfect' crime?
2) But because the shipment was shown as goods in transit - and therefore not technically coming through the border - the consignment was not inspected by Customs.


3) Instead, the shipment is unloaded in the secure Customs-controlled area in the airport, then repackaged and freighted to the final destination of Tonga.

4) The Crown alleges Gan had an "inside man" in the Customs-controlled area, Mosese Uele, who ran a freight-forwarding company called Ezi World Cargo.

5) In one such shipment from China, at least 250kg of ContacNT - which contains pseudoephedrine, the key ingredient in methamphetamine - was disguised as potato starch.

6) Inside the Ezi World Cargo premises, Uele switched the ContacNT with legitimate potato starch to be sent to Tonga. The boxes of drugs were put in a van and driven to a car park in Auckland - all while being followed by police.

7) "It was almost the perfect scam," said Crown prosecutor Scott McColgan, "but for Gan's involvement with two people, who unfortunately for her, were under surveillance by police. Otherwise it is very unlikely this scam would have ever come to light."

8) Police financial analysts say there are "vast amounts" of cash deposits in Gan's bank accounts which coincide with other food shipments from China destined for Tonga.