Police investigating the death of 21-year-old farm worker Eion Gebert near Opotiki believe there are likely witnesses to the fatal crash who haven't yet come forward and they are urging them to do so.
They also want to trace the passenger of a vehicle involved in the crash who left the scene before police arrived.
Mr Gebert was on his way to work on a motorbike at approximately 5am on Saturday, December 1, when he was struck by car travelling in the opposite direction.
A witness has reported that the car overtook a tow truck and three others cars immediately prior to the crash but only the truck driver stopped at the scene and spoke with police.
The driver of the car involved in the crash also spoke with police at the scene. However his passenger is reported to have left in a silver station wagon. Although police believe they know the identity of the passenger they have been unable to locate him.
Sergeant Ray Wylie said: "It may be that the drivers we have been told about knew there were other witnesses and therefore felt there was no need for them to stop.
However it is vital in these cases to ensure we obtain accounts from as many witnesses as possible so that the investigation is thorough and we can help Eion's family understand how and why he died.
"It is also essential in the interests of justice as we need to determine what, if any, enforcement action should be taken. It is important to stress that these drivers are being sought as witnesses. There is no suggestion that they have committed any offences and therefore they have nothing to fear from coming forward."
Anyone with information about this crash is asked to contact Opotiki police on 07 315 1112 or Whakatane police on 07 308 5255.