A Newshub investigation has discovered the raw cannabinoid chemicals responsible for multiple deaths around the country are being imported mainly from China and Spain.
In another alarming development, health authorities now fear the drug is no longer just being smoked - it's being snorted.
New Zealand is being swamped by mystery powders concealed inside boxes and envelopes. They're the raw material used to make so-called synthetic dope, and they're some of the chemicals that have killed at least 20 Kiwis so far.
In the first six months of this year, Customs found almost six kilograms of raw chemicals in 38 different border incidents.
Customs showed Newshub a trolley full of suspect packages. All of it was found in just one morning.
Most of these packages appear to be innocuous. One envelope simply has a name and address and a stamp, which indicates it's come from Amsterdam. Inside is five grams of a highly toxic cannabinoid. It's suspected a lot of packages like this are ordered online using the dark web.
So what exactly are these chemicals?
The Institute of Environmental Science and Research's (ESR) test data, which Newshub has obtained, shows it's mainly a substance called AMB-FUBINACA. That's been found in large quantities in Auckland.
But there are two other dangerous designer drugs also doing the rounds - 5F-ADB and MDMB-CHMICA. All of these have been linked to multiple deaths across Eastern Europe, the United States and Japan.
In the past eight months, all cannabinoids tested in Wellington were found to be the chemical known as 5F-ADB, a drug linked to deaths in Japan - 182 grams were detected.
Then there's the main offender - AMB-FUBINACA. The Southern District recorded about 68 grams, the central district, 31 grams.
Around 2.2 kilograms were detected by ESR as coming from seizures in Auckland.
A small amount of another strain was found in Counties Manukau. Again, this one has been linked to deaths overseas.
Alarmingly, Drug Foundation executive director Ross Bell says health authorities in the Hutt Valley think young people now might be snorting the raw chemical.
"We've seen in the last few years and possibly now... pills and powders that people are using and possibly using in different ways - rather than swallowing... snorting instead," says Mr Bell.
Here's where the drugs are coming from - China tops the list, followed by Spain and then the Netherlands.
"Five years ago, you would look for Contac NT. That was the main thing we'd look for, but now there's just a whole range of chemicals you've probably never heard of until you examine it," says Aaron, a senior Customs officer.
The Drug Foundation says super labs in China are churning out synthetic drugs.
"They're cheaper to make... They are made in these huge labs and it's just easy to sneak them into the country," says Mr Bell.
ESR says the drugs have little similarity to the effects of normal cannabis.
"What has been reported is that AMB-FUBINACA for example is 85 times greater than that of THC," says ESR forensic chemistry manager Kevan Walsh.
Mr Walsh is part of a team gathering intelligence on the cannabinoids hitting our shores. He expects more variations to appear.
This is a seemingly endless struggle for authorities - with no end in sight.