A New South Wales couple are facing the prospect of decades behind bars for the sexual assault and torture of their daughter.

Key points: NSW couple convicted of a combined 86 sexual assault charges

NSW couple convicted of a combined 86 sexual assault charges Father used barbed wire and chainsaw to torture daughter during rapes

Father used barbed wire and chainsaw to torture daughter during rapes Father raped daughter over 15 years, starting when she was five

The man and his wife, from northern NSW, were convicted of dozens of charges over the rape and torture of their daughter, which went on for 15 years, starting when she was five.

Sixteen of the 73 offences he was convicted of have a maximum sentence of 20 years, while two of the 13 offences the woman has been convicted of have 20-year jail terms.

Both the man and woman pleaded not guilty but were convicted by a jury earlier this year.

At a sentencing hearing today, Judge Sarah Huggett indicated many of the offences were categorised as extremely serious.

She will hand down their sentences tomorrow.

WARNING: This story contains details which some readers may find distressing.

The couple, who cannot be named for legal reasons, have a background in the teaching profession and elite sport.

Barbed wire and chainsaw used in assaults

During the hearing Judge Huggett listed the range of implements the parents used during the assaults.

The district court heard the man used a range of implements to torture his daughter during sex sessions that sometimes took place in a shed on his rural property.

Judge Huggett described how the man "took tangled barbed wire with loops on the end and nailed it around her", "locked her in a box overnight", "held a chainsaw to her neck", "held her head under water" and "put her on an ants nest".

The court heard that the man fashioned a number of crude implements to penetrate and cut his daughter.

Judge Huggett said the girl was often in "excruciating pain" and once a wrote out a desperate message "in her own blood".

The judge said the offences took place while the daughter was training at elite sporting events around Australia.

"If she did not perform a personal best [she] would be taken to the shed when they got home," she said.

The sexual assaults went unchecked for 15 years and sometimes took place on special occasions such as Christmas and Father's Day.

Mother complicit in assaults

The court heard the girl's mother gave her instructions about how best to please her husband.

"The mother told the victim it is better to make noises during sexual intercourse, with her father saying 'It would make it better for you and Dad'," Judge Huggett said.

The rapes continued during the girl's teenage years.

Once, when he suspected she was pregnant, the father made her drop medicine balls on her stomach as a training exercise.

The court heard that the father threatened to kill the girl on many occasions.

According to the evidence, he told her "If you tell anyone what happens here I will kill you. It is no-one's business. I own you."

Judge Huggett said it took the girl so long to come forward to police partly because her mother had "abused her role as a mother in the gravest way".

"She signalled that her husband's deviant conduct was normal," she said.

The case only came to attention of authorities in 2011 when the victim was admitted to a psychiatric ward.

After making a statement to police she helped them locate some of the instruments of torture that she had buried in the garden as a young girl.

DNA evidence on the instruments and her clothing found in the family shed corroborated her account and evidence from her sister.