WA Police have charged a third person over an alleged multi-million-dollar corruption scheme involving the state's Department of Communities.

Key points: Paul Whyte and Jacob Anthonisz were originally charged with stealing $2.5m

Paul Whyte and Jacob Anthonisz were originally charged with stealing $2.5m Police, who are still investigating, later said the amount involved could be up to $25m

Police, who are still investigating, later said the amount involved could be up to $25m Mr Whyte was a former assistant director of the WA Department of Communities

A 45-year-old woman is facing nine charges of official corruption, stemming from the allegations previously laid against former senior public executive Paul Whyte and another man, Jacob Anthonisz.

Mr Anthonisz and the woman are not public servants.

Mr Whyte and Mr Anthonisz were originally charged with using fake invoices to fraudulently take $2.5 million in taxpayers' money, but police later revealed in court the final amount allegedly stolen could be up to $25 million.

Police are now alleging the 45-year-old Beechboro woman "acted in concert with the two men already charged as part of this investigation".

She is due to appear in court on December 16.

It's believed Jacob Anthonisz co-owns racehorses with Mr Whyte. ( ABC News: Hugh Sando )

The allegations of corruption have shocked the WA Government.

Until his sacking last month, Mr Whyte was one of the state's most senior employees, employed as an assistant director general of the Department of Communities.

The charges have prompted the Government to set up a Public Sector Commission inquiry into the agency and tighten oversight and spending rules across departments.

Extent of racing interests becoming clear

Officials have also been probing Mr Whyte and Mr Anthonisz's interests in the racing industry, believing the pair owned around 100 racehorses between them in Australia and New Zealand.

That includes horses they owned in their entirety and others in which they held a syndicate stake, with those assets now frozen by the Corruption and Crime Commission.

Jacob Anthonisz was accused in relation to an alleged false invoicing scheme. ( Instagram: @jakesfolly )

WA Racing Minister Paul Papalia said some of animals would be cared for on a new Government-owned property to cater for retired racehorses, while others could be sold.

"There is some value to the horses, they are frozen assets," Mr Papalia said.

"Ultimately the whole thing will be resolved through either passing back to ownership through syndicates or sale of the horses."

Mr Papalia said it cost about $60 a week to care for each horse."