A former Mighty River Power engineer and his ex-wife are accused of fraudulently using their own businesses to bill the power company more than $2.3 million.
Paul Kenneth Rose and Jane Clare Rose are on trial at the High Court in Auckland on charges of obtaining by deception. They have denied the charges.
The Serious Fraud Office said Mr Rose, an electrical engineer, was in charge of identifying equipment and services needed for the Southdown power station in Penrose.
According to charges read out in court this morning, the couple sent almost 200 invoices to Mighty River Power from their own companies, but did not reveal their connection to the companies.
The Serious Fraud Office said the offending happened over seven years to 2012. At the time the company was a state-owned enterprise.
In his opening address to the jury, Crown prosecutor Nick Williams said Mr Rose initially used his first partner's name on company documents that he was controlling.
He said it was through these companies that Mr Rose sold goods and services to his employer Mighty River Power.
Mr Williams said Mr Rose told his then partner he needed her name on the documents so he could hide the company from an ex-partner and avoid increased child support payments.
When he later broke up with the woman she asked for her name to be removed from the company's documents and when that didn't happen she did it herself.
Mr Williams said Mr Rose later used his own mother's name.
He said neither women had experience in the industry of electrical engineering.
The Crown's case is that Rose, through his companies, would buy goods from a supplier and sell them on to Mighty River at inflated prices.
In one case goods were sold with a 1380 percent mark up. Mr Williams said the industry norm was between 20 to 30 percent.
Mr Rose also charged Mighty River for services, including $210,000 for an IT upgrade that Mr Rose carried out as an employee, the Crown prosecutor said.
Another example was paying a friend $1000 for six or seven days cleaning at a power plant and then billing Mighty River $5280.
Mr Williams said the scheme came undone due to a piece of detective work from one of Mr Rose's colleagues.
The colleague was looking into what Mighty River had spent on maintenance and one of the parts recently bought by the company caught his eye.
The item was an accelerometer which measures the vibrations of machinery and was purchased by Mr Rose.
Mr Williams said these highly specialised products rarely broke down or needed replacing.
The colleague was surprised a New Zealand company could source one and when he looked into company documents he noticed the director's first name was Jane and the company was listed to a Howick address.
Mr Williams said the man was aware that Mr Rose's partner's name was Jane and that they lived in East Auckland.
He called the company's number and when he asked for Mr Rose, he was given a cell phone number.
The man then got his wife to call the company, using a ruse that she was selling a gym membership. The woman on the end of the phone confirmed she was Jane Rose.
The man forwarded his concerns to Mighty River who employed a private investigator before calling in the police.
The trial has been set down for four weeks.