The leaders of a Bay of Plenty-based criminal gang that declared war on their rivals in an Underbelly-style saga of guns, drugs and violence have been found guilty of a raft of charges following a High Court trial.

Nine senior members and affiliates of the Mongols, including national president Jim Thacker, faced a multitude of drugs and weapons charges in the lengthy trial in Hamilton.

Following a months-long covert surveillance operation, police swooped on and arrested the entire senior hierarchy of the gang in June 2020.

A gang war was brewing in the Bay of Plenty, the police said, with numerous groups battling for the lion's share of the drug market there – and the Mongols were right in the thick of it.

The trial itself was filled with twists and turns, and dramatic tales of arson, gun battles between gangsters in the region's horticultural heartland, and an armed assault on the home of a Mongrel Mob leader's daughter.

It was also beset by numerous delays, including when some participants came down with Covid.

The jury of seven men and five women retired to consider their verdicts just before 4pm on Tuesday, following the two-day summing up of Justice Melanie Harland – a process that concluded on the three-month anniversary of the trial's start in mid-August.

They returned with their decisions at midday on Wednesday.

Thacker was found guilty of the vast majority of his 44 charges including discharging a firearm with reckless disregard, unlawful possession of prohibited firearms, participating in an organised criminal group, possession of firearms and ammunition, possession of methamphetamine for supply, supplying methamphetamine, possession of ecstacy for supply, possession of cocaine for supply, supplying cocaine, and money laundering.

He was found not guilty on four charges of possession of pistols, supplying methamphetamine, and possession of meth for supply.

He greeted the delivery of the verdicts with a scowl.

Meanwhile, most of his cohort were also found guilty of most of the charges they faced.

Among those who also stood trial was vice president Hone 'One-er” Ronaki; who was, unbeknownst to Thacker, operating a 'side hustle” supplying methamphetamine to Black Power members in Whakatane.

He was found on guilty on 26 out of 40 charges including of participating in a criminal group, discharging firearms with reckless disregard, supplying methamphetamine and possession of prohibited firearms – among others.

The gang's sergeant-at-arms Leon 'Wolf” Huritu was found guilty of 11 out of 12 charges, including possession of firearms, prohibited firearms, and methamphetamine for supply.

Jason '666” Ross, the head of the gang's Christchurch-based chapter, was found guilty of the three meth possession charges he faced, as well as one of supplying a class B drug.

Kelly 'Rhino” Petrowski, the gang's secretary/treasurer who took care of their affairs in Hawkes' Bay, was found guilty of four out of five drugs charges.

Another defendant, who was based in Auckland and has ongoing interim name suppression, was found guilty of 13 out of 14 drugs and gun charges, while gang affiliate Matthew Ramsden was found guilty of all 12 of his charges – which were mostly methamphetamine-related.

Prospect-turned-gang member Kane Ronaki was found guilty of three firearms and explosives possession charges.

Only one of the defendants, Te Reneti Tarau, was found not guilty of the two charges he faced – possession of methamphetamine for supply and conspiring to supply meth.

Following the delivery of the verdicts – and in spite of the objections of their accompanying prison officers – Thacker and Huritu embraced.

Justice Harland convicted the men and remanded each in custody until their sentencing on April 17 – including Tarau, who is remanded in custody on another matter.

The nine will be joined by about nine other men – also charged as part of Operation Silk and who had pled guilty before the start of the trial – for sentencing on that day.

'Thank you for the dignity you have shown today,” she told the defendants.

After, she turned to the jurors.

'This has been a long trial. A lot longer than expected. On behalf of the community I thank you very much for your service.”

She granted each juror immunity from having to participate in any other jury service for the next seven years.

The Crown case against the men hinged largely on numerous intercepted phone calls and text messages between the gang members, as well as the account of a Crown witness – a former gang insider who decided to turn against his former colleagues.

The witness, whose name has been permanently suppressed, was a former driver for Thacker and other members of the gang. He alleges he took numerous trips to Auckland, the South island and other parts of the country to transport drugs and guns for the gang.

The defence case – led by Thacker's lawyer Bill Nabney and Hone Ronaki's counsel Ron Mansfield KC – is that the witness' account was a largely fictional one, and that while the gang were involved in drugs it was nowhere near the volume alleged by the Crown.

-Mike Mather/Stuff.