How she became the live-in lover of an orchard worker while his own wife lived alongside them is a mystery. How she vanished after giving birth to his child is another.

Today marks the ninth anniversary of Ms Haigh's disappearance and sets the stage for an emotionally charged coronial inquiry, which begins at Parramatta Local Court tomorrow. More than 30 witnesses will give evidence, some of which has never been publicly aired.

Detective Sergeant Keith Price, one of two investigating officers still in the police force, said this is a story set to unfold ''like no other''.

Ms Haigh, after finishing school in Sydney, headed to Kingsvale in the state's south to earn money during the cherry-picking season.

At first she stayed with an aunt who lived in the area, which brought great relief to her mother, Rosalind Wright. ''Amber was slow in her thinking; she was delayed in some ways … She was definitely vulnerable and very easily led.''

It remains unclear exactly how, but the teenager ended up living with a local married couple, Robert and Anne Geeves, about 2001. In his marital home, and while his wife, Anne, resided there, Mr Geeves engaged in a sexual relationship with Ms Haigh, who became pregnant with his child and gave birth to a baby boy.

Then, on June 19, 2002, Mr and Mrs Geeves walked into their local police station and reported Ms Haigh missing.

They said that two weeks before, on June 5, they had made a four-hour road trip to Sydney and dropped her at Campbelltown station late at night so she could visit a sick relative in hospital.

But the police had reason to doubt the story. Another woman, Janelle Goodwin, 29, had also previously become pregnant with Mr Geeves's child while living with the couple.

Unlike Ms Haigh though, her fate could not have been more certain. Ms Goodwin was shot dead on the night of June 20, 1993. Police found her body the next day in a shearing shed behind Mr Geeves's farmhouse. She had been stripped naked and tied with twine from her ankles to her neck. Blankets wrapped her body and a plastic shopping bag was fastened around her neck.

In a police statement tendered to the court, Mr Geeves told police he could not recall what had happened to Ms Goodwin, other than they had both been drinking and become involved in a violent row that ended with Ms Goodwin being shot with a rifle through the nose.

He told police that in a panic he had hosed down the crime scene next to his farmhouse and stored Ms Goodwin's body in a wheelbarrow.

He was charged with murder, and pleaded not guilty. A magistrate discharged him owing to insufficient evidence. The ruling meant the case could be prosecuted in the future.

After Ms Haigh disappeared, police launched a search of Mr Geeves's 160-hectare farm , and journeyed deep into a series of abandoned mine shafts scattered across the property.

No body was recovered but, in a twist, the investigation into Ms Haigh's disappearance led to Mr Geeves being charged with murder over Ms Goodwin's death. Prosecutors were confident: they had ballistics advice and fresh witness statements.

When the trial took place in 2006, Mr Geeves was found not guilty. The jury concluded it had been a terrible accident. What they did not know was that it was the second time Mr Geeves had been acquitted of serious charges.

In August 1986, two 13-year-old schoolgirls from nearby Young went missing after they failed to return home from school. When they resurfaced more than two weeks later, one filed a statement to police alleging that she had been kept prisoner in a wheat silo and sexually assaulted by Mr Geeves. The other girl contradicted the claims. Mr Geeves was charged with the sexual assault of a minor but was found not guilty.

Mr Geeves has been subpoenaed to give evidence at the coronial inquiry.

The Sun-Herald does not suggest that Mr Geeves was responsible for any sexual assault, nor that he should have been found guilty in relation to his prosecution involving the death of Ms Goodwin.

It is also not suggesting that he was responsible for the disappearance of Ms Haigh.

Mr Geeves and his wife tried to retain custody of the son that Ms Haigh left behind. That bid was thwarted and the boy is being raised by Ms Haigh's relatives.

Her mother, Ms Wright, chooses not to dwell on Mr Geeves because, emotionally, she cannot afford to. But she does not believe her daughter ever made it to Campbelltown station.

''This is a very difficult time for myself and my family,'' she said in a statement. ''It will never be over for me until they find my daughter.''

eduff@fairfax.com.au