Mr Taiaroa was married to his wife Helen for 43 years.
Detective Inspector Mark Loper said police had widened inquiries, visiting the owners of blue 4WD vehicles as far afield as Te Awamutu.
Information from the public had allowed police to track the vehicle involved, believed to be a dark blue Jeep Cherokee, to its last known position on a road between Mangakino and Benneydale. The driver would have gone through a web of forestry roadways to get to the area and probably had local knowledge.
"They may have visited or moved through here and may be now living in Auckland or further afield; for that reason we want to hear from anybody who may have suspicion about who this person may be."
Yesterday, police divers scoured the Waikato River near the scene but wouldn't reveal what they were looking for. Police had an idea of the weapon involved in the murder and a description of the driver.