A suspended policewoman accused of supplying her uniform to a criminal who used it to steal a high-performance car has had her case dismissed.

Karis Rewa Charnley, 39, appeared in the North Shore District Court last month to defend charges of being party to impersonating a police officer and being party to theft and assault. The impersonating charge related to allegations she supplied her uniform to her boyfriend, Cameron Ross, who used it to steal a Mitsubishi Evo.

Ross was jailed for 12 months over the incident in June.

In a recently released decision Judge Brian Callaghan said he remained "suspicious" about Charnley's involvement, however he was "unable to be sure that she took part in the pre-planning of the offending".

There was also a "vacuum" in the evidence and the prosecution was unable to convince him beyond a reasonable doubt that Charnley was involved.

Last month the court heard Charnley met Ross in the corridor of the North Shore District Court where she worked as a jailor, in October 2011. He was waiting to have his 24-hour bail curfew relaxed.

They "bonded" over their shared love of the Illuminati and the apocalypse and formed an "unusual relationship" which became abusive.

Charnley was suspended from the police in mid-December after she was found to have "had an inappropriate relationship with a criminal and his family".

Ross used the uniform to impersonate a police officer and seize the car from a Devonport address on February 8, claiming it had been used in a hit and run. He used a seizure and impound notice where the car's ownership details were written out.

The car belonged to Jerome Kino - a friend of Charnley's son's - who had built it with his father and had it insured for $11,000.

Charnley had been a sworn police officer for seven-and-a-half years and she told the court in October she was "horrified" when she realised Ross had used her uniform.

She was arrested on February 14 and the stripped Mitsubishi Evo was found a month later at an address in Paremoremo. She resigned from the police on May 2.

- © Fairfax NZ News