The marriage of one of WA's worst sex offenders is one of the key factors why he should not be released from prison because of fears his wife could be added to his long list of victims, the Supreme Court has been told.

Key points: WA's dangerous sex offender laws were drafted with Garry Narkle in mind

WA's dangerous sex offender laws were drafted with Garry Narkle in mind Prosecutors are applying to keep him behind bars under the laws

Prosecutors are applying to keep him behind bars under the laws The court has heard Narkle's wife may give evidence in support of him

Garry Narkle, who is now 64, is fighting an application by prosecutors to have him declared a "dangerous sex offender" and be kept in custody under laws introduced in 2006.

The laws were drafted with him in mind, but were never applied to him.

At the time, then attorney-general Jim McGinty described Narkle as "a sex monster", with Parliament told his 40-year criminal record included the sexual assault of women, girls and boys.

Three years after the laws came into effect, Narkle raped a homeless man and was sentenced to 10 years in jail without parole.

Now that sentence has expired and prosecutors are seeking to keep him locked up indefinitely.

Prison calls reveal arguments with wife

In an opening statement to the court, state prosecutor Brent Meertens said psychiatrists who had interviewed Narkle in jail were of the opinion he posed "an unacceptable risk" of committing further offences if he was released.

Mr Meertens said one of the risk factors was Narkle's jailhouse marriage in 2011, which otherwise might be regarded as a stabilising factor.

He said in Narkle's case there were concerns his wife was at risk of being another one of his victims, with prison calls recorded between the two of them showing their relationship was marked by conflict and Narkle's abuse of her.

Narkle had shown "a very limited response" to sex offender treatment programs in jail, the court heard. ( ABC News: Alkira Reinfrank )

The court has listened to some of the calls in which the two are arguing, with Narkle suggesting his wife has cheated on him.

At times the woman is sworn at and abused by Narkle.

In one of the calls he also said he wanted a divorce as soon as possible, telling her he wanted to get "a decent woman, a good woman".

Mr Meertens said the couple met only three weeks before Narkle was taken into custody for his 2009 offences and their relationship was "largely untested".

"It is considered that his wife may be at risk of harm from him," he said.

Garry Narkle's victims include men, women and children. ( ABC News )

Mr Meertens also said Narkle was planning to live with his wife if he is was released, but that address was "known to certain persons" and because of his notoriety there were concerns there may be "vigilante actions against him".

There was also concern for the safety of the authorities who would have to visit the address to monitor and supervise him.

No reduction in Narkle's sex drive: prosecutors

The court was told Narkle had participated in sex offender treatment programs in jail, but he had "a very limited response" to them and one of the psychiatrists considered him to be "essentially an untreated man".

Mr Meertens said despite Narkle's advanced age and his health issues, including a heart problem, there did not appear to be a reduction in his sex drive.

He also said Narkle "engaged in impression management" and in interviews he tended "to give only responses that best advantaged him at the time".

That included information about his sexual functioning and what he had told his wife about his offending.

Narkle's wife sat in the Supreme Court's public gallery for the hearing and wiped away tears. ( ABC News: Briana Shepherd )

In telephone calls recorded just two months ago, the woman claimed Narkle had not told her before of his full history of offending, saying he had told her "different" things before and she had made decisions on things that were not true.

But as he listed some of his crimes to her, Narkle said he now accepted "total responsibility" for what he had done.

He said at the time he was "drinking and taking tablets" and was telling her only what he could remember.

"I wasn't responsible for anything before, but I am now today," he told her.

"I want you to know everything. I didn't want to wreck our relationship."

Wife wipes away tears in court as calls played

In another call recorded earlier this year, the woman told Narkle he had never told her before that he had "raped people".

"It's not very nice after 10 years for it to come out like that," she said.

The woman, whose identity is suppressed, sat in the public gallery for the hearing and wiped away tears as the calls were played.

The court has heard she may give evidence at the hearing in support of her husband.

Narkle's history includes allegations he sexually assaulted a 17-year-old girl in 2000.

She testified at three separate court hearings, but the case was dropped after Narkle won an appeal and a retrial was ordered, with the girl too traumatised to give evidence for a fourth time.

Chief Justice Peter Quinlan is likely to reserve his decision at the end of the two-day hearing.