A badly beaten teenage girl whose body was later put in a car and torched in a rural carpark was killed by multiple “gang-affiliated” people, her sister claims.

Four months have now passed since Ariki Rigby’s remains were found shoved in the back of a car that had been set alight in the River Road Recreational Reserve on the outskirts of Havelock North.

The 18-year-old was killed during a holiday to visit relatives – including her father – in Hawke’s Bay where she grew up. Her sister, Anaherā Rigby, believes her life was taken on the day she planned to drive back to her home in Auckland.

In the lead-up to Christmas, police said they believed possible witnesses to two Hawke’s Bay homicide investigations – Ariki’s and another into the unrelated 2018 violent death of Eddie Peters – were not coming forward due to the potential gang affiliations of those thought to be responsible.

Talking to the New Zealand Herald, Anaherā said she understood that police were making “good progress” with their investigation.

But she believed the killers’ - who she understood had gang links – had significant help in avoiding being found by police.

“It is sad to say that it is a gang-affiliated circumstance. I just hope that the people that do know something, do say something,” Anaherā said.

 “Gang-affiliated persons [did this]. There was more than one.

“For them to get away with it, there must have been a lot of them. And still to get away with it, they must have had a plan . . . if the police can’t find them now, obviously it [the incident and the ongoing freedom of the killers] was not an accident.

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Ariki Rigby had dreams of making music and had also considered moving to Australia to live with relatives. Photo / Supplied

“They have a system with trying to get away with what they did.”

The car which Ariki’s body had been shoved into was taken to the River Road Recreational Reserve either late in the night on September 2, or early in the morning on September 3. It was then set alight.

The burnt-out car was reported to police on September 3. But attending officers didn’t realise the charred remains inside were human.

The car remained there for a further two days before a dog walker realised the body was human and urged police to return to the scene. The dog walker revealed Ariki had suffered multiple bone breaks and fractures.

Police are reviewing their initial response.

The location where the car containing Ariki Rigby's body was torched is a popular destination for dog walkers. Photo / Neil Reid

On December 22, police made a further appeal for information about Ariki’s homicide, and also the death of Eddie Peters.

Peters was found badly beaten on the driveway of a family member’s home in Flaxmere on November 16, 2018. He died eight days later in Wellington Hospital.

Detective Senior Sergeant James Keene said police believed gang affiliations of those thought to be responsible were preventing possible witnesses from passing on vital information.

“We know there are people in our community who know what happened to Eddie and Ariki, and who was responsible,” Keene said.

“We also know there are a few reasons why people might not be talking – one of which is a belief that ‘narking’ is not the ‘done’ thing. My plea is that people set aside that belief and focus on what the right thing to do is.”

Anaherā said “our streets aren’t safe” until those responsible were located.

She made another appeal for those who knew the truth to have the courage to come forward.

“I know there are fears for their lives as well, and maybe fears for the safety of the ones they love or their children,” she said.

“But I just hope they find it in their hearts and see the pain that we are in.

Family of Ariki Rigby have placed flyers in shops around Hastings and Flaxmere appealing for information. Photo / Neil Reid

“She was only a little girl and the people that did this to her [or who knows the truth] would have people they love who are the same age as Ariki. I just don’t understand why they can’t look at those people and think, ‘Oh my gosh, someone could take them away from me any minute’, because that is what we have got to deal with for the rest of our lives.”

Ariki’s loved ones would not rest until the killers faced justice, her sister said.

Relatives have placed flyers around Hastings and Flaxmere in a bid to uncover information that could lead to arrests. The flyers also feature a Crime Stopper 0800 line to call with anonymous tips.

“We are still looking for her murderers and putting flyers up in the shops . . . we are doing everything that we can,” Anaherā said.

She had previously told the Herald said there had been false confessions given to police.

Ariki’s cousin, Hastings-based pastor Michael Ngahuka, urged whoever knew the truth to have the moral fortitude to tell police who brutally killed his loved one.

Ariki Rigby's oldest sister, Anaherā, and cousin Michael Ngahuka have made impassioned pleas for people with information to come forward. Photo / Supplied

“At the end of the day, this has happened in our community and they need to make a decision . . . will they be a part of [what happened]?,” Ngahuka said.

“If you know something or someone, and you know they were involved and you don’t bring any justice to that or share anything, you are a part of it in a sense.

“I don’t know how people can live with themselves like that . . . it has to weigh on the soul, it has to weigh on your heart. This heinous crime and act has happened. We just want justice.”

Family and friends of Ariki gathered where her body was found on Christmas Day.

A memorial garden with written, floral and solar light tributes to murdered teen Ariki Rigby has been erected at the River Road reserve carpark on the outskirts of Havelock North, where her body was found. Photo / Neil Reid

The memorial at the site includes solar lights, and handwritten, painted and assorted floral tributes.

Family members and friends also gathered at the site on what would have been her 19th birthday late last year.

Anaherā said it was “heart-breaking” to spend Christmas Day at a place that was linked to such sorrow, but loved ones had tried to remain as upbeat as possible.

“I made [the site] all beautiful . . . when I went there I was trying not to dwell on the past and the pain,” she said.

“We put a blanket out in the sun, had all the toys out on a blanket for the kids to play with, had the speaker blasting [music] while we were cleaning [the site] up, making her look all beautiful.

“Obviously, it would have been a lot better if she was with us, but we are trying our best with what we have.”

• Anyone with information is asked to contact police on 105 quoting file number 220905/1265. Information could also be provided anonymously to Crime Stoppers on 0800 555 111.