One of the last people to see missing Auckland woman Iraena Asher alive said she was "like a zombie" the day before her disappearance.

An inquest into the trainee teacher's death comes almost eight years after she mysteriously vanished from Piha, on Auckland's west coast, in the early hours of Sunday, October 11, 2004.

Today would have been her 33rd birthday.

The 25-year-old part-time model was last seen standing naked under a streetlight in the middle of the night, during a blustery storm.

Earlier, she had called police for help and instead of sending officers to help, they called a taxi, sparking public outrage and a wide-ranging overhaul of the 111 system.

Today Jesse Pragert, a friend of Asher's then-boyfriend, told the court about his first - and last - meeting with Asher, who suffered from bi-polar disorder.

Pragert had been out on the town the night before with his girlfriend, who was today granted name suppression, and spotted Asher's boyfriend, an old friend, in a bar. The three went to another bar together, where Pragert took an ecstasy pill.

Some hours later, they decided to go to his house in Piha, and stopped to pick Asher up on the way. Asher had been out with her boyfriend the night before, but went home early to her flat.

"She walked into the lounge like a zombie," Pragert said. "And she was spaced out."

Pragert and Asher's boyfriend went to get some beer from the supermarket, while his girlfriend stayed with Asher. On the boys' return, Asher had changed from her pyjamas into a long green skirt, "like something you would wear to a fashion show not the beach," Pragert said, "so we told her to change".

On the way to Piha, they stopped to get gas, which annoyed Asher and she became grumpy, he said. When they got to the Piha house, Asher began crying but wouldn't say what was wrong. She stopped when given a glass of wine.

From there, her behaviour got increasingly "out of it", Pragert said. At one point, she disappeared down to the beach and came back soaking wet. They gave her new clothes, but she took them off, instead wearing a duvet and occasionally dancing naked around the room.

"She was seductive," Pragert said. "But didn't want to do anything because she wanted to wait to have sex after marriage." This was despite engaging in a sexual relationship with both Asher's boyfriend and her ex-boyfriend of four years, Julian Dyson.

Asher had broken up with Dyson the week before her disappearance to be with her new boyfriend.

Twice, she got into bed with Pragert and his girlfriend, then got out again. At some point, Asher's boyfriend left, and then while Pragert was still in bed, around 8pm, Asher got up and left herself.

He heard her talking on the phone, then the door slam, and she was gone. That was the last he heard until the police came knocking early the next morning, he said.

Asked by the Coroner if he thought he should have got her medical help, Pragert said no. "I'd never met her before. I though that was just the way she was."

Dyson said their relationship had been "full-on" from the start, but he was aware of Asher's bi-polar. "She was really aware of her condition."

The relationship was tumultuous, he said. "She thought I was cheating on her. But she was actually the flirt." He also described how Asher was impulsive and could be emotional.

The couple had moved in together 10 weeks before Asher disappeared, and the relationship ended badly when he found out she was sleeping with her boyfriend.

"Before I left," he said, "I made a bonfire out the back to burn personal things. I did this to upset her."

He said though he had been working nights and hadn't seen Asher often in the month before they broke up, she told him she missed a couple of her lithium pills. To make up, she'd take extra.

Despite all of that, Dyson said he didn't believe Asher would have killed herself. "She was very driven... if she was angry it was at other people other than herself."

"I don't think she committed suicide. I'd like to think it was accidental."

He spoke of how she loved to swim - and was good at it, as she'd been a surf lifesaver.

"She knew rips and she knew how to navigate them."

Earlier, the court also heard from police how Asher's behaviour grew increasingly bizarre and erratic in the days before she disappeared, which they said likely culminated in her death by drowning.

Police counsel Simon Moore told Coroner Peter Ryan that Asher, a "striking" woman and the second of four girls born to parents Mike and Betty, was diagnosed with bi-polar disorder in her mid-teens.

Though Asher kept the condition under control with Lithium tablets, it could be exacerbated by stress, causing a "relapse" of unpredictable and bizarre behaviour, Moore said.

Officer in charge of the original investigation, Detective Senior Sergeant John Sutton, told the court how during that day Asher began to act strangely.

She was picked up by passers by, Julia Woodhouse and her son Henry, and taken to their home. They gave Asher a shower and some food, then put her to bed. But at 1am she fled the house into the storm.

Asher was last seen naked, under a streetlight by Zachary Nixon and his girlfriend Simone Ross. They hid and watched her "address" the streetlight, Sutton told the court. She then appeared to kneel down, and kiss the ground, before turning towards the beach.

"They followed her. The last they saw her as she moved toward the beam of the last streetlight near the beach. They were astonished she seemed to disappear into the darkness," Moore said.

A "massive" search found no sign of Asher. Police suspected she may have been "self-medicating", but could not establish that fully, Sutton said.

However, he believed her erratic behaviour was the sign of a full manic episode.

Sutton said the most likely scenario was that Asher had walked into the sea and drowned. Two other possibilities - that she had gone into the bush, or met with foul play - could not be substantiated, he said.

- © Fairfax NZ News