David Campbell, 48, of Murrumbateman, was arrested along with Rohan Arnold, 44, and Tristan Waters, 34, in a dramatic raid on a five-star hotel in the Serbian city of Belgrade last week.

Serbian authorities say the three men were arrested in the middle of a money transaction.

A bag with about $1 million in foreign currency and a gun were seized.

Mr Campbell was being held on suspicion of possessing the unauthorised gun, authorities said.

The arrest followed a nine-month investigation into the shipment of 1.2 tonnes of cocaine, concealed in steel tubes, that arrived from Brazil onboard a Chinese container docked in Sydney Harbour.

The drugs had a street value of up to $500 million, the Australian Federal Police and Australian Border Force said.

The men, along with a Lebanese man also arrested in the raid, were expected to face charges of conspiracy to import commercial quantities of a controlled drug.

As the Post has previously reported, Mr Campbell was general manager of engineering firm Mass Steel when it was established in Goulburn in January 2011.

Mr Campbell was appointed to the position by the head of the firm, his co-accused, Rohan Arnold.

The company, trading as Old MS Pty Ltd, had leased space in the north Goulburn premises of DME Kermac Engineering.

In May 2011, Mr Campbell told the Post that production had doubled and the firm had employed 22 more workers, in addition to its existing 20.

In September that year, Mr Campbell said more contracts were flowing in and there was more than enough work to keep people employed for some time to come.

But in June 2012, the company went into liquidation with an alleged $11.5 million debt, including $1.42 million in worker entitlements.

Liquidators Kazar Slaven subsequently conducted an extensive investigation into a string of Mr Arnold’s companies.

Despite the fact some workers and suppliers never recovered their money, Mr Arnold was back in business by 2013, trading under another company name, Solutions for Steel Imports Pty Ltd, formerly known as Solutions 4 Steel Pty Ltd.

Mr Arnold was listed as the company’s director, Kazar Slaven and the Australian Securities and Investment Commission (ASIC) confirmed.

“Since 1996 Rohan Arnold has owned and operated the business which has grown to now be one of the major structural steel suppliers on the eastern seaboard,” the Solutions 4 Steel website stated.

The website pointed to several “ongoing” projects including the Australian Institute of Police Management, Canberra Hospital’s acute mental health building and Cessnock Correctional Centre.

All of the projects had been completed and were also previously listed on Mass Steel’s website. Mr Arnold later told the Post the website was “outdated” and “didn’t reflect [its] current business”. 

“I consult and give advice to tier-one contractors on the import of steel,” he said at the time. “It’s a completely different business to Mass Steel because I’ve learnt my lesson through the Mass Steel experience and had a change of life.”

Mr Arnold and Mr Campbell are believed to have been close business associates over at least the past seven years.

Mr Arnold was most recently involved in the South Eastern Livestock Exchange (SELX) at Yass as a director.

Together with SELX director Brendan Abbey, he was also constructing the Western Victoria Livestock Exchange at Mortlake, due to open on Monday.

Mr Arnold and Mr Abbey are also directors of a company, Yass Industrial Park Pty Ltd, proposing to build another service centre at Yass.

The plan has attracted controversy, with a rival service centre operator claiming it was not permissible in the zone.

Last Thursday, Mr Abbey said he was shocked to hear on the 6am news of Mr Arnold’s arrest. The Post does not suggest any involvement on his part.