The jeep seized from the man identified as the prime suspect in the murder of roadworker George Taiaroa is still being held by police and is key to detectives' inquiries.
The officer leading the investigation has again characterised the motive as one that would appal people even as the widow of the slain man says her husband was killed for being Maori.
Tomorrow will be the one-year anniversary of Mr Taiaroa's death. He was shot and killed at the stop-go checkpoint where he managed traffic diverted from State Highway 1 north of Taupo at Atiamuri.
A witness saw Mr Taiaroa fall dead after approaching the passenger window of a blue Jeep Cherokee, which has since become central to the police's hunt for the killer.
Police later seized a Jeep Cherokee near Rotorua, taking it from a farm owned by the parents of the key suspect, inadvertently named by police in the inquiry.
Detective Inspector Tim Anderson said police had explored all avenues before becoming convinced over the events which took place a year ago.
"We still believe that the Jeep Cherokee vehicle we seized in the weeks following the murder was involved. We still have that vehicle and we are continuing to carry out work with that vehicle as part of the investigation. Although I am still not prepared to discuss the motive for the murder, our position on that, and the fact that it would appal any reasonable person, has not changed.
"My position also remains the same when it comes to not making comment on individuals. But we still have one prime suspect."
Mr Anderson issued a fresh call for information, saying he wanted the person responsible - and those who knew him - to understand that the investigation was active.
"The last year has not been easy for George's family and this week will no doubt be particularly difficult. He was a doting family man and the impact of his loss is never far from our minds. It drives us forward and makes us all the more determined."
Dr Helen Taiaroa, who had four children with Mr Taiaroa, said the past year had been extremely hard on the family, especially knowing him as a loving patriarch without any secrets that might make him the victim of a violent death.
Dr Taiaroa, who has kept close contact with police, said racism lay behind Mr Taiaroa's death. He was murdered "for being Maori".
The suspect told a Sunday newspaper he did not kill Mr Taiaroa. He has also said his Jeep Cherokee was purple, rather than blue. He said police had raised racism during questioning, which he rejected.
Anyone with information is asked to contact the investigation team on 0800 Kingswood (0800 546 479). Information can be also provided to the organisation Crimestoppers on 0800 555 111.