A former general manager of a gold mill is facing serious charges over an alleged million-dollar theft in WA. 

Patrick Rhyan Keogh is among five people charged over the alleged theft of 8,465 tonnes of gold-bearing ore with an estimated value of $1.18 million from the Greenfields Mill in Coolgardie.

Mr Keogh has pleaded not guilty to stealing as a servant from his former employer.

The 40-year-old has also been charged with money laundering. It is alleged that money was transferred from processing the ore into bank accounts which some of the accused could access.

Mr Keogh was general manager for FMR Investments for 12 years. His role involved oversight of the operation of the company's Gordon Sirdar gold mine and the Greenfields Mill.

The mill processes gold from a range of sources, including several mining companies and professional prospectors.

Mr Keogh was released on $100,000 bail but ordered to appear in the Perth Magistrate's Court next week.

Two of his co-accused, 73-year-old Geographe man Christopher Robert Burns and 31-year-old Boulder woman Morgan Whitney Dombroski, are due back in court in coming weeks.

A 55-year-old man from Somerville and a 49-year-old man from Broadwood will face court later on money laundering charges in coming weeks.

Detectives executed nine search warrants at residential and commercial properties in the Kalgoorlie and Busselton areas as part of their investigation.

The matter was investigated by the state’s Gold Stealing Detection Unit.