It was launched after the cocaine was found hidden in a suitcase carried by Mexican David Negrete Nevarez, who arrived at Auckland Airport on a Lan Chile flight from Santiago in December 2011.
Nevarez was among five people arrested before McGannan was traced.
Using covert surveillance techniques, the Organised and Financial Crime Agency watched Nevarez deliver the cocaine to Auckland woman Samantha Margaret Gemmell, 27, who in turn passed it to Adrian Marquiss Kemp, 31, in a Mission Bay carpark.
Watched by police, Kemp transferred the package containing the drug to Wellingtonian Brendan John Clarke, who agreed to find buyers for the cocaine, which was 80 per cent pure, after the original purchaser pulled out.
Nevarez, 43, had previously pleaded guilty to importing and possession of cocaine for supply and been sentenced to seven years in prison.
Gemmell and Kemp each pleaded guilty to one charge of possession for supply and were jailed for two years, six months and two years, 10 months respectively. Clarke, a 37-year-old self-employed builder who worked as an Earthquake Commission contractor inspecting damaged Christchurch homes, pleaded guilty to possession of cocaine for supply and will spend four years and eight months in prison.
A Wanaka man he allegedly delivered the package to has pleaded not guilty and will stand trial in Christchurch later this year.
According to the police summary of facts, McGannan came under police scrutiny after sending Gemmell a text message from London that read: "It's all sorted out ... I've spoken to the people and sh**."
It is understood he knew Gemmell and Kemp from his schooldays on Auckland's North Shore.
Police said McGannan later told them he was contacted by a friend in London who "pressured" him into arranging others to help deliver the drugs.
Crown prosecutor Aaron Perkins said a second charge faced by McGannan, of importing the cocaine, would be dropped at sentencing.
Outside court, his lawyer Graeme Newell told APNZ his client was a "ring-in" rather than a kingpin.
"It must now be acknowledged that he was neither a kingpin nor an importer. In other words, he was not a mastermind."
Mr Newell said that McGannan never realised the impact his actions wouldhave on his friends and he now regretted that.
"Obviously he needs to accept what he's done, pay his penalty and put this behind him."
Cocaine costs about $325 a gram in New Zealand.
Law enforcement agencies believe Auckland is a transit point to the Australian market and beyond.
McGannan will be sentenced next month.
Operation Gringo - pass the parcel
* Daniel McGannan, extradited from Britain. Pleaded guilty to organising the supply of 3kg of the Class A drug via South America.
* David Negrete Nevarez. Smuggled the parcel from Chile and was caught by customs at Auckland International Airport. Sentenced to seven years in prison.
* Nevarez passed the cocaine to Samantha Margaret Gemmell in Auckland. Gemmell was sentenced to two years and six months.
* Gemmell passed the package to Adrian Marquiss Kemp in a Mission Bay carpark. He was sentenced to two years and 10 months.
* Kemp forwarded the parcel to Brendan John Clarke in Wellington. He was sentenced to four years and eight months.
* Clarke allegedly sent the cocaine to a fifth man who pleaded not guilty and will go on trial later this year.
