Detective Inspector Tim Anderson said there were no firm suspects, although they had a description of a man, which they were keeping to themselves. An arrest was not imminent, and police were yet to find the weapon used in the attack.
"And we are no closer to a motive; so we're still chasing that."
Yesterday police set up five checkpoints around south Waikato, stopping motorists and asking them whether they had seen anything of note around the time of Mr Taiaroa's killing.
Mr Anderson said potential witnesses had offered new information, but he would not comment on what it was.
"A number of motorists offered information they thought might assist us," he said.
"I can't comment in any detail about the information and it's too early to say where any of it will take us, but the fact that we identified more potential witnesses made it a very worthwhile exercise.
"It also convinces us that there is still information to be found, so I can't stress enough the importance of telling us what you know, no matter how small or irrelevant it may seem."
One motorist stopped at yesterday's checkpoints had been at the Tram Rd scene immediately after the shooting but had not previously spoken to police.
Mr Anderson said police had also interviewed Mr Taiaroa's family.
He would not elaborate when asked if Mr Taiaroa had any history of conflict or violence.
Associates of the roadworker denied this when asked by the Herald.
Locals believe the killer has ditched the car in the Waikato River, hid it in the bush, or even buried it.
"Take your pick of places around here, there are a lot of places like the Pureora Forest or the Waikato River that you can get rid of a car," said a Tokoroa woman, who asked to be called only by her first name, Laura.
"He's certainly not going to be driving it any more."
Pukeko and Bull owner Tina Schrider said she was not concerned for her safety, even though a killer was on the loose.
"Not at all, I highly doubt that he's in this area, he's probably far away from here by now."
She also thought the killer would have ditched the vehicle, "and hopefully would have shot himself as well".
A few of Mr Taiaroa's HEB Construction colleagues still stay at her hotel, but they kept to themselves, she said.
Mr Anderson said police had spoken to all the witnesses in the immediate vicinity, including the driver of a green vehicle they had been keen to contact.
Police were not discounting the possibility that the offender could be a local.
"It has the appearance that the offender was familiar with the road network here - as to where the person could be, that's anyone's guess," he said.
Mr Anderson admitted to a slight frustration at the investigation's progress but said police had a number of "avenues of inquiry" that they were pursuing.
"This is a difficult inquiry - there's no doubt about that," he said. "It's frustrating in the sense we haven't resolved it yet.
"We still think there's a number of opportunities for the public and the community of the greater North Island to help us resolve this.'"
* Can you help? Anyone with information about the death of George Taiaroa should call police on 0800 Kingswood (0800 546 479) or Crimestoppers on 0800 555 111.
