Key Points:

13D Frank St was a mess when police began their investigation.

Bourbon boxes, pizza cartons and kids' shoes had been chucked through a hole in a broken ponga fence where the Rotorua rental property backed on to a reserve.

Empty bottles littered the ground inside the fence, and out the back of the small three-bedroom house in the low-income neighbourhood of Koutu was a table with broken legs and a baseball bat leaning against the wall.

Inside, a bowl of half-eaten noodles was on a table.

This was the scene of the crime; the mess the aftermath of a 21st party which raged one Saturday afternoon and night with loud music and brawls while a battered, malnourished little girl lay dying.

You'd need a Big Brother camera to get across the horror of the last days of Nia Glassie's miserably short life.

Failing Big Brother, child witnesses in the trial of who killed Nia, who assaulted her and who neglected her the most, probably told it best.

The children's identities were suppressed but what they said in court was hard to listen to.

They sometimes mixed up what happened when and ran incidents of abuse together. It didn't matter. What came out loud and clear was the nature of the abuse that went on and on, usually when Nia's mother was at work, but sometimes when she was there.

What was done to Nia was callous and violent, perpetrated by a group of no-hopers who lived and partied together, who smoked pot together and who for one reason or another didn't like the little girl they failed to protect.

Nia Maria Glassie was three. They thought she was ugly.

In court, via a television screen, a little girl says: They were kicking her to the couch.

Who?

Wiremu and Michael.

What with?

With their feet.

They kicked Nia in the head, and she points to the front of her head.

How many times?

Three times.

Then what happened?

She was falling asleep.

How hard was the kick?

Hard as a rock.

Wiremu put her to bed.

Sometimes Nia would bleed but they don't care about it. They just keep on smashing her, she says.

They put her in the corner and they kick her to the wall and she gets bumps on her head.

The worst thing, in this child's mind, was when Michael Curtis lifted Nia to the ceiling by her neck and her hips and when she touched the ceiling, he let her go.

This interview, and that of another child, was recorded when Nia was alive, though barely so.

She was in hospital, on a ventilator. Her brain injury, left untreated for 36 hours, was so severe parts of her brain tissue had died.

Another child tells how they spun Nia on the clothesline as fast as they could. Her voice is soft and shy.

They put her into the drier, too, she says.

The drier is in court. A Simpson with a small round door, 28cm in diameter.

Next to it, a tiny pink T-shirt with the words "Miss Cutie".

This is the T-shirt Nia was wearing when, finally, she was taken to hospital.

Who did this, a kindly woman asks the girl, about the drier.

Wiremu and Michael Curtis, she says. But it was Michael Pearson's idea.

She said to Michael Pearson, don't do it.

Why did you say this, asks the woman.

Because she's just a little kid, says the girl.

Michael Pearson told her to shut up.

We listen in appalled silence.

The defendants don't look appalled. Perhaps they're bored. Though, sometimes in court they laughed and whispered and often they tried to stare down the reporters covering the trial.

It was hard to read the stares, but certainly there was challenge in those largely blank eyes; even in court it seemed they were making lame attempts to be menacing.

That was until they listened to each other's statements as told to police when it happened, when they were all so quick to blame each other.

Then their body language changed dramatically and the main offenders, the Curtis brothers, had to be separated by guards.

The woman asks the second girl more about the clothes drier.

You turn it right up, replies the girl, and it gets hot then it dries your clothes.

Nia was screaming, she says, so they put her on the clothesline and they spinned her as fast as they could so she could fall off.

She did fall off, the little girl says. Three times. On her head.

They put Nia in the drier like "a ball", the girl says.

They turned the switch, the one with lots of numbers on it, up too high and Nia kicked the door open but they just put her legs back in.

They were laughing but this little girl didn't think it was funny.

The clothesline and the drier were on different days, and they were not what killed Nia. The kicks to the head killed her.

The girl also told how "they" shoved her in the sandpit and threw a basketball at her. But first they'd taken her jeans and undies off her and they'd pushed her in the sandpit on her bottom.

She was crying loud so they turned up the radio so the neighbours didn't hear. Then they watched DVDs and got some vegetables ready for Michael Curtis' 21st party.

When Lisa Kuka, Nia's mum, came home from work, around Shortland Street, she and this girl went out leaving the Curtis brothers, Nia and another child in the house.

Nia was all right when they left, but when they came back she was floppy and wouldn't wake up.

Nia "slept" the rest of Friday and all of Saturday and Sunday.

Both children told of wrestling moves the grown-ups got off the PlayStation 2 - which Wiremu had stolen - that they saw performed on Nia.

These moves are hard to envisage. If you don't have a PlayStation take a look at YouTube and type Smackdown! v Raw in the search bar. Then imagine adults doing this to a 3-year-old.

The children were cross-examined. They were sitting in a room next to the courtroom and their words and images came to the trial through a TV screen.

Five defence lawyers and the Crown questioned them and one of the defence lawyers suggested the wrestling was "funsies" that got a bit too hard. The jury obviously didn't agree.

Nia was a second-class citizen in that house. When it didn't make them angry and get her another hiding, they seemed to take pleasure in her crying.

One of the defendants told how she would sometimes whimper instead of crying because she knew if she cried she would get something else.

In New Zealand's long list of child abuse cases, children are often killed when a carer snaps in anger.

These ones were mean and violent, seemingly because they were bored, or perhaps because they could.

A police officer talked about a "pack mentality". One would do something so another one would do something else.

The abuse was normalised and it escalated. The brothers didn't play sport or work, there was booze and pot, though no suggestion of P.

They didn't have much money so were home a lot and found ways to entertain themselves.

Every day in court, a new horror unfolded. Jurors would stare at the defendants in disbelief.

Lisa Kuka, Nia's mother, received plenty of those stares. She knew at least some of what was happening to her daughter but did nothing to stop it, not even when Nia wouldn't wake up but could still have been saved.

Lisa Kuka, it seems, grew from a nice little girl into a woman whose life revolves around men and who demonstrated a frightening submission to them.

She was the 17th of 19 children. A former primary school teacher told us that while poor, the Kukas seemed a nice family. Lisa's older sisters, twins Louise and Linda, looked out for her.

They were not terribly bright, but they were good girls and they always had lunch and shoes.

"I look at her now, the photos of her on TV and she's got such hard eyes, absolutely hard," the teacher said. "I remember her as a rather bubbly, little bit silly-headed, giggly little girl."

She can't think what happened to Lisa, but says a lot of low socio-economic women in Rotorua get into playing the poker machines and going to housie and pubs.

"Their lives are very thin ... Thin in terms of interests and hobbies and ambitions. It would be the most unrewarding life I can imagine, and I've seen a lot of them like this. It's a sad thing."

Lisa has already found another man, one who promised to take her on holiday to Niue, his homeland, if she got off.

She had her tubes tied after Nia, but by the time she hooked up with Wiremu Curtis she had six children.

She was 34; Wiremu was 16 and not long out of school. He was described in court as "a slow learner".

His lawyer called him stupid and used his stupidity as a main plank in his defence.

Family members on both sides disapproved of the relationship. In court, in a police interview, we heard Lisa admit she loved Wiremu and that her loyalty was to him.

Whatever it was she saw in him, she was content to entrust the care of her daughter to someone who couldn't have been more woefully inadequate.

When Wiremu dobbed in his older brother Michael - the smart one - and Michael's girlfriend, Oriwa Kemp, during a police video interview screened in court, he was sobbing and sniffling and his story became wilder and wilder.

Michael was incensed at what he heard, and when they left for a break his fists were clenched. When they came back a guard sat between them and the cocky body language was gone. Michael was stony and Wiremu jerked his knees, slouched and squinted and chewed on something furiously.

The next day some of his fingers were plastered - apparently because he'd punched a wall - and he appeared to deteriorate from then on.

While his lawyer was giving his defence, Wiremu scribbled on a paper towel. A peek showed it to be some kind of rap song, but the words were incomprehensible.

A long list of abuses perpetrated by Wiremu against Nia was detailed in court.

He and Michael come from a very big long-established Rotorua family. Actor Cliff Curtis, famous for his role in Once Were Warriors - the movie about domestic violence which was inspired by the notorious Ford Block in Rotorua - is a cousin of the Curtis brothers' father, William.

William sat at the back of the courtroom every day. "The proud father," a policeman said cynically.

We can't say much about William, 49, because he faces his own trial over allegations that he, too, abused Nia.

His is said to have pulled a scarf around her neck until she went purple, at a previous address, which he denies.

Outside court, William told us he joined the Black Power at 14. When asked why his side of the family went into the gangs, he would only say "we've all got different ways".

He said when he split up with the brothers' mother, Michael, then 8, went with him and Wiremu spent some time with his mother and also with an aunt in Northland.

"I was a hard man," William said, though he reckons he'd left the gang. "He [Michael] was brought up the same way that I was, I was hard with him but."

They lived all over the place. Michael, he reckons, went to hell and back with him.

Michael was said in court to have bashed his girlfriend, Oriwa.

When Wiremu got together with a woman old enough to be his mother, William senior says he freaked out.

"A lot of people told Boy, [Wiremu] to finish with her. He wasn't ready to rear kids, he had a life out there, out in this world. He had dreams, he was going to go to Aussie."

William's bond, though, was with Michael. he is said to despise Wiremu.

When Wiremu was dobbing in Michael, William would mutter things like "this is bullshit".

In court, Michael was painted as the ringleader who looked after his brother, though police said to us it was more like bullying. It was Michael who came up with the story that Nia had fallen off Wiremu's shoulders.

Police described Wiremu as a "mummy's boy" and it was his mother, Tania Te Para-Heta, he ran to when Nia finally went to hospital.

He was rambling and incoherent and still drunk from the party, telling her how Nia had fallen off his shoulders. She encouraged him to talk to police again, not believing the story.

She seemed nice in court. Dignified and honest. Her appearance to give evidence brought the first real emotion from the brothers when she blew a kiss in their direction. It was as if they couldn't, or wouldn't, look at her, and they cried. A police officer told us their mother is disgusted with them. She lives in Australia now.