One of the largest criminal trials in New Zealand history is under way in Hamilton, more than two years after police swooped on the Mongols gang in the Bay of Plenty.

Operation Silk, as it was known by the police, resulted in the arrest of the entire senior hierarchy of the gang on a raft of drugs and weapons charges.

The weapons allegedly in the group's possession include AK47s – Soviet designed assault rifles – as well as military-style semi-automatic (MSSA) firearms including a Bushmaster XM15-E2S, a pistol grip pump action shotgun, Molotov cocktails and a homemade bomb.

At the time of the arrests in June 2020, police alleged a gang war was brewing in the Bay of Plenty region, and numerous groups were battling for the lion's share of the drug market there.

There are nine defendants taking part in this trial, facing 118 charges. It began on Monday in the High Court in Hamilton, with the empanelling of a jury of six men and six women, arraignments, and the opening remarks of Justice Melanie Harland.

The trial has been set down for 10 weeks. There are 241 Crown witnesses, although not all need to be called to give evidence.

Among those on trial is the Mongols' president, Jim David Thacker, who is charged alongside gang members Hone Ronaki, Leon Huritu, Jason Ross, Kelly Petrowski, Matthew Ramsden, Kane Ronaki, Te Reneti Tarau, and another man who has interim name suppression.

The charges the nine face include participation in an organised criminal group; unlawful possession of prohibited firearms, explosives and ammunition; reckless discharge of a firearm; possession of cocaine, methamphetamine, MDMA (ecstasy), and 25I-NBome (also known as N-bomb, a form of synthetic LSD) for supply; money laundering; aggravated robbery; and attempting to pervert the course of justice.

Firearms seized during the 2020 raids.

The charges span the period between January 1, 2019, and June 23, 2020. They are laid in connection to events that allegedly happened in Tauranga, Auckland, Christchurch and other parts of New Zealand.

The reckless discharge of a firearm charge relates to an incident at Haukore St in Tauranga, when 96 rounds were allegedly fired into the lounge of a house affiliated to the Mongrel Mob gang.

One of the two aggravated robbery charges relates to the alleged taking of a Greasy Dogs printed hooded sweatshirt from a man in Mt Maunganui. The Greasy Dogs are another rival Bay of Plenty gang.

There is a massive police and security presence at the courthouse, with dozens of staff in attendance. Because of the number of defendants, most have been seated in the courtroom's lower public gallery, with an equal number of Corrections staff by their side.

In her opening remarks, Justice Harland urged the jurors to avoid referring to any information about the trial. There had been much media coverage at the time of the arrests and she urged them to put any recollections of that to one side – and to avoid reading any ongoing media reports on the trial.

'You must be objective in your assessment of the evidence ... You need to keep an open mind until you have heard all of the evidence.”

The empanelling process, earlier in the day, was a lengthy one. Two other courtrooms had to be used to accommodate the pool of potential jurors, and – with one Crown prosecutor and 11 defence lawyers in the room on Monday – there were more challenges than usual made by the lawyers to some of the would-be jurors during the selection.

Other potential jurors had to be excused by the judge because they had some compelling reason why they would not be able to participate.

Cash hidden in a sock draw.

Once selected, the 12 jurors had to undergo rapid antigen Covid testing; all tested negative.

The courtroom for this trial is unusually crowded. Extra shelving has been brought in to cater for the numerous files and boxes of documentation. Stacked up by the desks and at the rear of the courtroom, they add to the fortified air of the proceedings.

Prosecutor Anna Pollett will open the Crown case against the defendants on Wednesday.

-Stuff/Mike Mather.