But knowing something to be true and proving it - beyond reasonable doubt - are two different things.
Drug investigations need manpower, months of time and expertise beyond the capabilities of the Kawerau station.
Or for that matter even the organised crime squad in the wider Bay of Plenty police district, whose staff are not ring-fenced and often seconded to major crime investigations like homicide inquiries.
Frustrated by his inability to get traction with his bosses at headquarters in Rotorua, the constable went over their heads.
He wrote directly to Police Commissioner Mike Bush with his concerns.
In essence, the Mongrel Mob were running Kawerau and the police needed to act. Now.
Bush moved quickly to task the National Organised Crime Group (NOCG), which is responsible for most of the country's best covert drug investigations.
Detectives within NOCG have been at the forefront of methamphetamine inquiries since the early 2000s.
They were used to targeting the top of the supply chain: international crime syndicates, hundreds of kilograms of drugs hidden in freight containers, covert surveillance and tapping phone communications.
What was happening in Kawerau - essentially the retail end at the bottom of the supply chain - did not meet the traditional threshold for NOCG.
But the order came from the very top. So in August 2017, Operation Notus started.
The High Court granted interception warrants which allowed the police to listen to phone conversations, plant tracking devices, as well as hidden surveillance cameras.
These days, most criminal groups use encrypted communications in a bid to evade detection.
Perhaps emboldened or complacent, the members of the Kawerau Mongrel Mob did not seem to be as careful in their tradecraft.
They spoke in code but in an unsophisticated manner.
Around 300 staff were involved in the raids in which nearly 30 firearms were seized and $2 million of property frozen.
Among the vehicles towed away was the F-150 Raptor, as neighbours watching from their lounges waved to police
More than 50 people were arrested; the Mongrel Mob were no longer in charge.
"It's time this country woke up to the bullshit that's going on around here. This is going on all around the country," said Malcolm Campbell, the mayor of Kawerau.
"This is a scourge on society. When you've got young kids walking around fried out of their heads, it's not a good thing. It's not good for the town and it's not good for anyone. We're picking up the pieces."
Campbell, who is also the town's butcher, was at a press conference speaking alongside Inspector Kevin Taylor and Chris Marjoribanks.
He's lived in Kawerau most of his life, been in the job for eight years.
He said there was a huge surge in methamphetamine consumption around 2016.
Families that Marjoribanks had grown up alongside were now prostituting children to pay for the P habit of the elder members of the whanau.
"It shocked me. I would never have believed it if someone else had told me those stories. It went much wider than that - some physical abuse that was really quite horrific," says Marjoribanks.
"The deprivation of children in these homes, no food, no proper clothing, is borne deep within the families."
The malaise of methamphetamine settled across the town. It became acceptable.
He urged greater funding and collaboration between government agencies, as well as community groups such as Tuwharetoa.
"We know the families, we know the community. We see the impact of methamphetamine on a daily basis ... the deprivation in homes, lack of food, domestic violence, impact on our children," he said.
Yet, more than a year down the track after the first Notus raids, Kawerau still does not have a fulltime alcohol and drug counsellor.
It took nearly a year wrangling between Tuwharetoa and the BOP District Health Board to approve the funding earlier this year.
Those who have never struggled with addiction - or deprivation - can underestimate the importance of having a trained counsellor in town, says Marjoribanks.
"People are quick to judge. Why don't they attend the appointment in Whakatane?" says Marjoribanks, of the nearest addiction counsellor about a 30-minute drive away.
"Well, there's no public transport. For many of our people, they may have a car but it's not registered or warranted. That's a big fine.
"Or they might not have enough money. And this sounds ridiculous, to those who live organised lives, but sometimes attending a 3.30pm appointment in three weeks' time just falls out of their memory.
"The intent is there but you need resource to achieve the commitment."
And while Marjoribanks has been fighting for more resources, he's the first to say change must come from within.
"I think it's totally unrealistic to expect someone with a long-term addiction, or is struggling with a sense of identity or self-worth, to make that step away from drugs dependency without some real motivation, something to build their confidence on, and that takes time.
"It takes dedicated time to walk the journey with them. Most importantly when they trip or regress, it's not closing the door and saying well you've had your chance, don't come back, it's opening the door with a warmth and smile on your face and encouraging them to come in and walk the journey again."
Long term, as well as greater drug and alcohol counselling in Kawerau, Marjoribanks believes the answers to addiction can be found in education and employment.
It used to be teenagers but now children as young as 11 and 12 have significant meth habits, he says.
Significant investment is needed for social and mental health workers in schools, says Marjoribanks, who advocates for a national education programme which starts in primary school.
"Youth tend to listen to youth. There are some young people we know who have had some challenging journeys; I think youth would listen to them.
"Adults tend to think young people don't take information on board. But I've seen clear examples where it walks with them for life."
For those who have hit rock bottom, Marjoribanks says there's more work to be done than simply ticking the rehabilitation box.
Most people relapse once they come back into the community, so Marjoribanks says Tuwharetoa is working on a new structure of support.
"They come back to a home that's safe, clean...If they're just coming back to an unemployed situation sitting in space without any motivation to get up the next day, with no positive future ahead of themselves, I think that's where most of them return to their addiction," says Marjoribanks.
"We need jobs so they're not sitting around with time on their hands. We've got to provide other opportunities and aspiration."
It's the sort of holistic approach championed by Te Ara Oranga, a trial project in Northland where the police work closely with the DHB, iwi and community groups to help people out of addiction and into employment.
Those who are using methamphetamine are identified and visited by police. But instead of locking them up, they're offered treatment and support.
The value of Te Ara Oranga and the impact of Operation Notus in cleaning up a community is clearly appreciated by the senior detective in charge of organised crime in New Zealand.
Around 600 meth users were identified in Kawerau, population 6000, says Detective Superintendent Greg Williams.
"Of course we're going to tackle organised crime, holding those groups and individuals accountable. But we've got to tackle methamphetamine from all sides.
"That's why Te Ara Oranga is so special. You've got everyone working together to put real support in place for families and the community. I'd love to see [the pilot] go out across the country."