A Sydney nurse who shot and decapitated her ex-lover has been granted an early release from jail, despite failing to reveal the whereabouts of her boyfriend's remains.

In 1997, psychiatric nurse Kathy Yeo and an accomplice shot Christopher Dorrian three times before severing his head.

The head was later discovered washed up inside a sports bag on the banks of the Cooks River at Tempe.

Kathy Yeo murdered her boyfriend and severed his head. Picture: 9NEWS (9NEWS)

In 2000, Yeo was convicted and sentenced to 24 years in jail with a non-parole period of 18 years, which expires next month.

Mr Dorrian's family was hoping with the introduction of new "no body, no parole" legislation in NSW Yeo would not be granted an early release from prison unless she revealed where the rest of the remains are.

The victim's son stormed out of the Parole Authority hearing today after the board granted Yeo the early release, even though she failed to provide any closure to the Dorrian family.

The rest of Christopher Dorrian's body has never been found. Picture: 9NEWS (9NEWS)

"She's a narcissistic, cunning, vile bloody creature and she does nothing but brag about it," an emotional James Dorrian said outside court.

"There's people doing life for much lesser crimes.

"I just think it’s ridiculous."

James Dorrian called the decision a "joke". Picture: 9NEWS (9NEWS)

Speaking to A Current Affair after the verdict, James Dorrian spoke about coming face to face with his father's killer for just the second time.

"She's not worth it," he said.

"I shouldn't even look up at her, but a good part of me wants to get my hands on her."

Yeo could be released by July 13. Picture: 9NEWS (9NEWS)

James said he didn't understand the decision to release Yeo from jail.

"It's a monstrous act, she should be locked away for life," he said.

Former detective David Wylie, who with Erris Shiels locked up Christopher Dorrian's killers, said Yeo was "an evil, manipulative woman that has never shown any remorse".

"It would appear that the authority is not bound by that piece of legislation, which is disappointing," he said.

Mr Shiels said it was "extremely disappointing" for the Dorrian family to not have final closure.

"However, in saying that, we must respect the decision of the parole board as well," he said.

Victims' advocate Howard Brown is angry the new laws failed to deliver any closure for the family.

"That piece of legislation by this decision has just become impotent," Mr Brown told 9NEWS.

"We may as well not have it.

"This is where the system fails."

Correctives Minister David Elliott said he was exploring avenues of appeal.