Terina Pineaha admits manslaughter of cyclist Emma-Jane Kupa, 11, in Flaxmere

A drunk woman who was also high on methamphetamine was driving to the home of the woman she was convinced was sleeping with her partner when she fatally ploughed into a young girl who was biking with her sister to the dairy.

On Friday, 34-year-old Terina Pineaha appeared by audio-visual link in the High Court at Wellington, where she admitted to a raft of charges, including Emma-Jane Sylvia Kupa's manslaughter.

The court heard that just before the crash, Pineaha's car reached estimated speeds of up to 105km/h in a 50km/h zone. Shortly after the car's speed was recorded, she struck the 11-year-old on the Chatham Road crossing in Flaxmere, on January 30.

Emma-Jane was cycling behind her 15-year-old sister, who was on a scooter, on their way to the dairy in Scott Drive.

The impact threw Emma-Jane into the air, before she landed 25 metres away on a grass verge, beside Ron Giorgi Park.

Pineaha's borrowed Holden Vectra slid on the wet road over the footpath and grass verge, striking 10 wooden posts on a chain fence before coming to a stop.

A pedestrian approaching the crossing just before the crash felt the wind from Pineaha's car as it passed him.

Members of the public rushed to Emma-Jane's aid, performing CPR until emergency services arrived. But she could not be revived and died at the scene from head injuries.

'I was going too fast'

At the time, Pineaha told police she'd turned down Chatham Road with rage and was screaming to herself and accelerating.

"By the time I saw the bike, I was going too fast and didn't have time to brake," she said.

She told police she was "in rage" because of her partner's perceived infidelity with a woman, whose name was suppressed by the court, and "was thinking of going to smash her".

At the court hearing, Pineaha put her head in her hands as the summary of facts was read out.

According to that document, on the morning of the crash, she bought $50 of methamphetamine and alcohol with a friend, before returning to a Hastings house, where they'd started drinking about 10.30am.

During the drinking session, Pineaha drank several cans of Cody's bourbon premix and Cruisers vodka premix, mixed with straight vodka. She also took at least five or six puffs of methamphetamine from a glass pipe.

After taking the methamphetamine, Pineaha was described as being emotionally "up and down" and "all over the place", crying one minute and then happy the next.

About 2pm, Pineaha borrowed the silver Vectra and left the house. It's not known where she went, but the summary stated that she was drunk when she left the house and was over the legal limit when police breath-tested her after the fatal crash.

At 5.38pm, she arrived at the house in Flaxmere Avenue, which belonged to her partner, with whom she had an on-and-off relationship.

There was a vehicle parked on the front lawn, which belonged to the woman Pineaha believed her partner was being unfaithful with.

Pineaha deliberately drove into the rear of the car and parked behind it.

Her partner and sister came outside, and a heated argument followed. The woman she thought was sleeping with her partner also came outside.

The two women fought, first on the driveway and then on the road, before being separated, and the woman went back inside.

Pineaha got back into her car and drove into the woman's vehicle twice, while continuing to abuse her partner.

The 11 minutes she spent at the house were captured on CCTV and showed Pineaha being aggressive and highly agitated.

When she left Flaxmere Avenue, she told police she was driving to the woman's house. On her way, she drove into the back of a white Nissan van as it waited to enter the Chatham Road roundabout.

The van's driver pulled over, expecting Pineaha to stop. Instead, she kept going, narrowly missing another vehicle and driving around the traffic island into the wrong lane to head south down Chatham Road. She again took off at speed.

From the roundabout, she travelled about 865m south along Chatham Road, a suburban street lined with houses.

Moments later, on this street, she fatally struck Emma-Jane.

Pineaha was breath-tested by police at 6.37pm and blew 595mcg of alcohol per litre of breath, above the legal limit of 400mcg.

In court, she admitted charges of manslaughter, consuming methamphetamine, wilful damage, driving with excess breath alcohol, dangerous driving and failing to stop.

The court heard that at the time of the incident, Pineaha was serving a one-year sentence of supervision for possessing methamphetamine and other charges. She was also convicted of possessing methamphetamine in 2018.

Justice Dale La Hood remanded Pineaha to remain in custody until her sentencing in the High Court at Napier in July.

*This story originally appeared in the New Zealand Herald.