Police are seeking a vehicle seen parked up near where George Taiaroa was shot dead shortly before it happened.
The roadworker was killed at Atiamuri in south Waikato two weeks ago.
Police said today a dark-coloured 4WD believed to have been parked on a nearby road before the fatal shooting was of interest to the investigation.
A farmer travelling in a tractor on Ongaroto Rd from Whakamaru towards Atiamuri on the afternoon of March 19 told police he saw the 4WD parked on the road and it later travelled behind him on Tram Rd towards a traffic controlled point manned by Mr Taiaroa.
The 4WD did not try to pass the tractor and appeared to drop back as it neared the traffic control point, resulting in the vehicle being stopped by Mr Taiaroa, said Detective Inspector Tim Anderson .
"We've been working with the tractor driver to pinpoint the timings of his sightings and everything suggests that this is our vehicle of interest, a Jeep Cherokee. A minute or so later George was shot,'' he said.
Police want to hear from anyone who travelled along Ongaroto Rd on March 19, particularly between the hours of 2.30pm and 3.15pm who may have seen the vehicle or anyone acting suspiciously.
Mr Taiaroa returned from his lunch break about 25 minutes before he was killed, said Mr Anderson.
A motive for the shooting. has not yet been established.
"It's been two weeks now since George was killed and we have found nothing to suggest that George was anything but a friendly, hard-working, family man.''
Anyone with information is asked to contact the investigation team on 0800 Kingswood (0800 546 479) or anonymously via Crimestoppers on 0800 555111.