Charges have been dropped against two brothers who were accused of an illegal worker scam at their Carabooda properties, marking the end of an almost five-year legal ordeal that is believed to have cost taxpayers millions of dollars.

Key points: Michael and Minh Canh Le's properties were raided by law enforcement officials in 2014

Michael and Minh Canh Le's properties were raided by law enforcement officials in 2014 They were accused of using foreign nationals to work on their farms, and covering it up

They were accused of using foreign nationals to work on their farms, and covering it up An earlier trial was aborted and another collapsed in May 2018, in a lengthy ordeal

Hundreds of law enforcement officials were involved in a series of highly publicised raids on semi-rural properties north of Perth in 2014 which came about after 12 months of surveillance and investigation by state and federal police.

Cars, firearms, cash and computers were seized.

More than 180 foreign nationals were taken in for questioning.

Michael Le and his brother Minh Canh Le were accused of using foreign nationals to work on their fruit and vegetable farms and then covering it up in an elaborate money laundering scheme.

Sorry, this video has expired Hundreds of law enforcement officials were involved in the highly publicised raids

The case went to court, but one trial was aborted and another collapsed in May 2018.

The second had been scheduled to run for 10 weeks but was abandoned after a series of delays dragged it out for almost eight months.

The delays were blamed on thousands of documents that were disclosed by Commonwealth authorities during the trial, requiring a string of lengthy adjournments so that they could be examined by the defence and then considered by the judge about their admissibility.

There were further adjournments to accommodate the increasingly frustrated jury members by letting them take pre-arranged holidays, attend appointments and get hospital treatment.

'Enormous resources' wasted: judge

At the time, the Chief Judge of WA's District Court, Kevin Sleight, called for an inquiry into the handling of the case — independent of the Commonwealth Director of Public Prosecutions — to consider the "enormous resources" that had been wasted.

In August, the charges that were the subject of that trial were discontinued.

Michael Le said it was a "big relief" to have the charges dropped. ( ABC News: Charlotte Hamlyn )

On Tuesday a remaining two, relating to money laundering, were dropped.

Charges against bookkeeper Lien Bich Thi Nguyen were also vacated.

Outside court Michael Le said the five-year battle had cost them more than just their business.

"It is a big relief, this has been very hard for myself and my family," Mr Le said.

"It's been very emotional, mentally draining as well.

Law enforcement officials conducted raids north of Perth in 2014. ( Supplied: Ch7 )

"What my father set up in 35 years and handed down to the family is ruined.

"Nothing can fix that."

Mr Le would not say whether he would pursue compensation for the loss of his livelihood over the past five years.

"I think the least the commonwealth prosecution and police can do is an apology," he said.

Minh Canh Le was accused of using illegal foreign nationals to work on fruit and vegetable farms. ( ABC News: Charlotte Hamlyn )

'Australia's biggest criminals'

Minh Canh Le's lawyer, Denis O'Haire, said both his client and the community had a right to be angry about the cost of the lengthy legal saga.

"Its been a difficult period," Mr O'Haire said.

"There was a lot of hullabaloo when the matter broke, five years ago now, and they were made out to be Australia's biggest criminals.

"We find five years later that nothing's happened, millions of dollars of legal costs defending themselves, the district court resources depleted for 18 months."

He said he planned to speak to his client about seeking financial compensation.

The brothers left the court with a group of supporters.