Police are asking for sightings of a dark-coloured hatchback that was seen near a fatal crash near Pokeno at the weekend.
The vehicle was spotted driving alongside the car that crashed into a truck on the Southern Motorway.
One person was killed in the collision.
Witnesses have reported that the hatchback didn't stop after the crash, and police would like to speak to the driver.
Anyone with any information is asked to contact police on (09) 261 1310, or to contact Crimestoppers anonymously on 0800 555 111.