A mother and father have been sentenced to lengthy jail terms for the sexual abuse and torture of their daughter over a 15-year period in northern New South Wales.

Key points: Both parents deny guilt, show no remorse, judge says

Both parents deny guilt, show no remorse, judge says Father found guilty of repeatedly raping girl since she was five

Father found guilty of repeatedly raping girl since she was five Pair worked in teaching profession, had links to elite sport

The judge noted that both parents still deny their guilt and have shown no remorse.

The 59-year-old father was sentenced to 48 years in jail and will first be eligible for parole in 2049, with Judge Sarah Huggett indicating he will likely die behind bars.

The girl's 51-year-old mother was given a 16-year sentence, with a minimum of 11 years, for her role in the prolonged abuse.

She was convicted of 13 offences including child rape and will first be eligible for parole in 2027.

The father was found guilty by a District Court jury of 73 offences, including repeatedly raping the girl from when she was five years old.

On the first day of sentencing, 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.

"He completely disregarded and exploited his youngest daughter's vulnerability," Judge Huggett said during the sentencing.

"Simply put — he did what he did for his own completely depraved and sadistic reasons."

Community 'hoodwinked' by trusted parents

The pair, who cannot be identified for legal reasons worked in the teaching profession and also had links to elite sport.

Judge Huggett said the community around the family was "hoodwinked" into trusting the parents.

The judge also described how the mother was complicit in the sexual assault of her daughter.

"She breached the trust her daughter held in her in the gravest way," Judge Huggett said.

"[She] intentionally manipulated her daughter's moral and emotional development … in circumstances where she should have protected her daughter."

Incest uncovered after victim went to psychiatric ward

There were two daughters in the family, and both gave victim impact statements at a sentencing hearing in Sydney in September, describing their parent's abuse as "putrid acts of torture".

The incest and sexual abuse began when one of the girls was five years old, the court heard.

The case came to attention of authorities in 2011 when the victim was admitted to a psychiatric ward, and her parents were arrested in 2013.

The judge said the victim now suffered from post-traumatic stress disorder and dissociative identity disorder.

Additionally, a psychologist told the court: "the lack of protection care and comfort from either of her parents led to disassociation as a primary survival strategy".