The Serious Fraud Office is to investigate the failed finance company, Nathans Finance. The company went into receivership in August, owing creditors nearly $170 million.
The move follows a complaint made by the appointed receivers, PriceWaterhouseCoopers.
The SFO says the investigation is likely to take some time and details cannot be discussed at this stage. However, the office's chief executive, Grant Liddell, says it is expected to be a complicated case.
Mr Liddell says eight fraud investigations into finance companies are in progress.
This week, the Securities Commission laid criminal charges against four Nathans directors, and also against the chairman and two directors of another failed company, Bridgecorp.