More than $5 million was fraudulently acquired by a former Fremantle Ports employee who remains on the run overseas, West Australian police believe.
The revelation comes as two contractors previously engaged by the port authority became the latest to be ensnared in the corruption investigation.
Police in June issued arrest warrants for Giacomo "Jack" Merolla and his wife Daniela Merolla.
The pair, both aged 54, are believed to still be on the run overseas, while their son and daughter have since faced charges relating to the alleged rort.
It's alleged Giacomo Merolla created several shelf companies within Australia and overseas, and used them to profit from fraudulent contracts.
The full extent of the associated financial benefits is still being investigated but police say to date, about $5.2 million has been identified as being transferred overseas to bank accounts controlled by those shelf companies.
Police on Tuesday said the owner of an electrical services business who previously worked as a Fremantle Ports contractor had been charged with corruption offences.
Merolla allegedly sent fake invoices to the 44-year-old man from Southern River from a private business he had registered.
The contractor then allegedly invoiced Fremantle Ports for that amount as well as an additional margin on top for himself, allowing both men to benefit.
Police say this took place 33 times between January 2019 and February this year, with the contractor receiving just over $3700 in payments.
The owner of a marine services business has also been charged after allegedly carrying out the same practice on 13 occasions last year.
It's alleged the 36-year-old from Edgewater also earned $3700 in payments.
Both men have been charged with multiple counts of acting corruptly as a public officer and will face court this week.
Neither are employees of Fremantle Ports.
Police believe the Merolla couple left Australia earlier this year and have since attempted to dispose of their Australian-based assets.
"Investigators continue to work closely with foreign law enforcement agencies, including Interpol, as well as other Australian law enforcement agencies in the investigation of this matter," police said.
Their son and daughter were arrested after detectives searched homes and a storage facility, seizing more than $70,000.
Paolo Vincenzo Merolla, 23, and Tiziana Merolla, 28, have both pleaded not guilty to property laundering charges.
They are expected to return to Perth Magistrates Court on November 17.
Australian Associated Press