Detectives from the Financial Crime Squad arrested a Mornington Peninsula man as part of their investigation in relation to allegations of false invoicing linked to a union and a private company.
A 74-year-old Mt Eliza man was interviewed by appointment in relation to fraud related offences.
He was subsequently released pending further enquiries.
Two search warrants were previously executed on May 15 at residential addresses in Mount Eliza and Tullamarine.
The investigation commenced in October 2023 after information was provided to police in relation to allegations of an estimated $2.7M deception believed to have occurred over a five-year period.
The investigation remains ongoing.