One of the straw directors in the Plutus Payroll scam, one of the largest alleged tax frauds in Australian history, has pleaded guilty to a raft of offences including dealing with the proceeds of crime, drug possession and multiple firearm offences.

Simon McIntyre, 48, an associate of the Nomad outlaw bikie gang, was arrested in February this year when he and his young daughter arrived at Sydney airport on a flight from Armidale.

In McIntyre's car, which was parked at the airport, police found a loaded black Ruger pistol, $5000 in cash, a large machete-like knife, a smaller military knife and three UHF two-way radios.

In the cabin he built on his remote property in Meryla, near Moss Vale, police found $2.4 million in cash hidden in a Louis Vuitton bag, 13.4 grams of the drug ice, and more prohibited weapons including an automatic rifle, a Norinco SKS rifle with a folding bayonet, and a double-barrel, 12-gauge shotgun.

For 14 years McIntyre worked in the Sydney headquarters of RailCorp, quitting suddenly in mid 2015.

His new business partners included property developer Daniel Hausman, a former bankrupt, and Peter Larcombe, an associate of the Comanchero bikie gang, who would later die in mysterious circumstances in Los Angeles.

On May 18 McIntyre had already been languishing in jail, bail refused, for three months when police swooped, arresting nine people in relation one of the biggest white-collar frauds in Australian history.

One of those arrested was McIntyre's "boss", Hausman. Others were Adam Cranston and his sister Lauren, whose father Michael was a deputy tax commissioner.

Also arrested were good friends Jason "Jay" Onley and Simon Anquetil, Daniel "Big D" Rostankovski and lawyer Dev Menon. The scheme allegedly skimmed $130 million of tax using a web of payroll companies, run by straw directors.

Both McIntyre and Larcombe's mother, Judith Reed, were listed in court documents as being straw directors, who were used as "fronts" to hide the involvement of others.

Larcombe was alleged to have been an early participant in the ATO fraud and was involved in several businesses with Adam Cranston.

In late 2014 or early 2015 Larcombe fled to Dubai. Rumours swirled among the alleged ATO fraudsters that Larcombe had departed with millions of dollars from the ATO fraud.

McIntyre went to visit Larcombe in Dubai in February 2016 along with another business partner of Larcombe's, Christian Madison, also known as Christian Budd-Madison.

 Fairfax Media can reveal that Madison's company, Hartford Investments, shared the same office in Cross Street, Double Bay, as Adam Cranston's businesses.

When Madison's company collapsed in 2016 owing almost $5 million, the major creditor was Uneek Consulting, a company police alleged was controlled by Adam Cranston and Antequil. Uneek is listed as a creditor claiming a debt of $3.25 million from Madison's failed company Hartford Investments.

Another listed creditor is Madison's close friend, nightclub boss Eric Jury.

Only three weeks before he jumped to his death at Los Angeles airport in August 2016, Larcombe caught up with McIntyre in LA.

Larcombe's death was seized on as a unique opportunity for the alleged conspirators should authorities catch up with them. Larcombe, 38, was to be blamed for the corrupt scheme, according to a call intercepted by police in February last year.

"So I need to put down ... the list of directors for everyone's coverage ... but obviously Peter Larcombe was running this," said solicitor Menon.

In another conversation, also tendered in court, Menon told Adam Cranston's sister Lauren that if they were ever questioned, they should say that 'Peter ran the whole thing'."

On Friday District Court judge Paul Conlon indicated that McIntyre will be sentenced in June next year.