The Perth father at the centre of the so called "evil 8" paedophile ring has had another year added to his record jail term for further sex offences against his daughter, including violently raping her when she was only 10 years old.

Key points: A year will be added to the man's existing 22-and-a-half-year sentence

A year will be added to the man's existing 22-and-a-half-year sentence His daughter told police he raped her when she was 10, even earlier than first thought

His daughter told police he raped her when she was 10, even earlier than first thought The man began "grooming" his daughter when she was just eight

WARNING: This story contains graphic content that some readers may find upsetting.

The 45-year old man, who cannot be named to protect the identity of his daughter, is already serving a 22-and-a-half-year sentence — believed to be the longest term ever handed to a sex offender in WA — for more than 60 offences against the girl.

They included his own abuse of her, and offering her up for sex to at least six strangers while he either watched or participated, when she was aged between 11 and 13.

He was charged with a further six offences last year after investigators conducted another interview with the girl, who is now in her late teens, and she disclosed further abuse at the hands of her father.

The man pleaded guilty to the charges with the District Court hearing one of the offences happened when the girl was just 10 years old.

She tried to stop her father, but he hit her in the eye and raped her as she cried.

Prosecutor Alan Dungey said the girl also cried and "attempted to put up a fight" on other occasions but her father abused her anyway.

Mr Dungey said another the time the man calmed his daughter down by telling her he would buy something for her.

Daughter suffers post-traumatic stress

Most of the latest offences happened at their home, where the court heard the man began "grooming" the girl when she started living with him when she was about eight years old.

It was alleged that before that the father had started "deliberately isolating" his daughter from her mother, but in his submissions the man's lawyer, Angus Hockton, said that was not the case and the girl had chosen to go and live with her father.

The father had separated from the girl's mother years earlier.

A victim impact statement was provided to the court from a psychologist who has been treating the girl, which said she now has post-traumatic stress disorder, a fractured relationship with her mother and conflicted feelings about her father.

The girl was again interviewed by police as an older teenager, prompting fresh charges against the man. ( AAP: Joe Castro )

The man appeared in court wearing prison greens and it was revealed that in jail he is being housed in a self-care unit where he can cook his own meals.

Mr Hockton said the man wanted to complete sex offender treatment programs, but has been told he won't be eligible for years because of the length of his sentence.

But Mr Hockton said his client was keen to do this as soon as possible because he recognised he was going to have to deal with many issues.

"When I ask him what he wants to achieve from it, he said he can turn around and say sorry to his daughter … but that doesn't carry much weight without knowing why, and he would like to be able to explain why he did what he did …" he said.

Victim feels 'utterly betrayed and manipulated'

In his sentencing remarks, Judge Laurie Levy praised the girl for displaying what he called "courage and determination" in detailing "the evil" the man had perpetrated against her.

He said the girl felt "utterly betrayed and manipulated" and while the man had represented himself in a psychological report as "a protective and loving father, nothing could be further from the the truth".

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Judge Levy imposed sentences of up to five years' jail for the six offences.

However, because of what is called "the totality principle" — which means a sentence cannot be imposed that is "crushing" and leaves the offender with no sense of a useful life after being released — he ruled that all but one year be served at the same time as the man's original jail term.

That means the man will first be eligible for parole in 2037 when he will be 62 years old.