National Crime Authority bombing accused Domenic Perre went into business with a self-taught gunsmith to convert semi-automatic firearms to be fully automatic in the year before the 1994 explosion, a court has heard.

Key points:

  • Allan “Gadget” Chamberlain said he first met the accused at a firearms shop
  • He told the court Mr Perre was part of a group of regular customers
  • Prosecutors allege Mr Perre took weapons and detonators to Mr Chamberlain for “safekeeping”

Allan “Gadget” Chamberlain is giving evidence in the Supreme Court against Mr Perre, 63, and is expected to be on the witness stand for the next two weeks.

Mr Perre has pleaded not guilty to murdering Detective Sergeant Geoffrey Bowen and attempting to murder lawyer Peter Wallis in March 1994.

It is alleged that Mr Perre sent a parcel bomb to Sergeant Bowen at the Waymouth Street headquarters of the National Crime Authority (NCA), which killed the officer and injured the lawyer once it was opened.

Prosecutors allege that Mr Perre’s hatred for the NCA and Sergeant Bowen started when Northern Territory police seized a $20 million cannabis crop at Hidden Valley Station in August 1993 and started investigating organised crime within the Italian community.

It is part of the prosecution case that Mr Perre handed his cache of weapons, bomb-making books and detonators to Mr Chamberlain for “safekeeping” ahead of the blast.

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The aftermath of the NCA bombing.

Mr Chamberlain today told Justice Kevin Nicholson that he first met the accused while working at Central Firearms, in Prospect, when he asked to buy body armour in January 1993.

The 66-year-old said Mr Perre was part of a group of regular customers called “The Backdoor Boys” and he would restore firearms for him.

He said by late 1993, Mr Perre had told him about the police raid at Hidden Valley Station.

“He brought the subject up and he was essentially telling me that he was under pressure — I believe, financial and mental stress,” he said.

Domenic Perre (left) is accused of sending a parcel bomb to the victim.(ABC News)

Prosecutor Sandi McDonald SC asked Mr Chamberlain if he and the accused discussed “going into business together”.

Mr Chamberlain told the court that he gained the skills and knowledge to convert semi-automatic firearms to be fully automatic by using a small plate as a “drop in”.

“I agreed to that. He would arrange to have these items laser cut. For doing that, we would effectively go 50/50 on the profit of the conversion.

“At that stage, I was charging $100 for a conversion on a SKK — it was a very easy conversion.”

Witness imported body armour from US

He told the court that he was nicknamed “Gadget” by the owner of Central Firearms because he was “always tinkering with something” and his firearm conversions were considered “magic”.

Central Firearms in Prospect is where Domenic Perre and Allan Chamberlain met in 1993.(Supplied.)

On Wednesday, Mr Chamberlain told the court that he was a volunteer in the Country Fire Service during the 1980s and became an agent for US companies so he could import fire-fighting and rescue equipment into Australia.

He said over the years, he branched out and was in contact with corrections and police about importing other items, including body armour.

“In all, over the years, I think I was an agent for 167 American companies,” he said.

Geoffrey Bowen was killed by the bomb at the NCA office in March 1994.

He told the court that in 1990, he reached out to a company called Second Chance — that was based in Michigan — about whether he could have the rights to import body armour to Australia.

“To me, it was exclusive and at that stage, they were higher-priced items than what I was used to,” he said.

He said he was given approval to do a demonstration at the now defunct Hindmarsh police station in front of officers in December 1990.

“I used an officer’s pistol to highlight the fact that, in their job, probably their greatest threat was their weapon being taken and used against them.

“It was pre-arranged that I would demonstrate the vest, but I had not informed them that I was going to shoot myself.”

Mr Chamberlain told the court that the demonstration was “dramatic and successful” because he sold 22 vests worth $28,000.

The trial continues.

Debris from the blast on Waymouth Street.(Supplied: SA Supreme Court)