Paul David Jensen, 42, has pleaded guilty to the same charges as Karu.
Police found more than 370 plants hidden in secret rooms fitted with fluorescent lights, reflective lighting, fans, extraction vents, heaters, digital thermometers, water filters and fertiliser. Karu and Jensen sold the cannabis by the pound (454g) for $3000 to $5000.
As hydroponically grown cannabis yields three or four crops each year, the police allege the drug cultivation from the seized plants could earn between $3.3 million and $7.4 million. This is disputed by Karu and Jensen.
A third defendant, Mark Lloyd Pedersen, has pleaded guilty to two charges of cultivation and one charge of possession for supply. He has denied a third charge of cultivation, selling the Class-C drug and participating in an organised criminal group.
He will stand trial next February with his partner Sharon Claire O'Neill and Andreas Johannes Turk, who have pleaded not guilty to all charges.