The death penalty would not be enough punishment for a man who murdered his ex-girlfriend and her two-year-old daughter, their family has told a Sydney court.

Daniel Holdom, 43, faced a sentencing hearing on Friday after pleading guilty to murdering his former girlfriend Karlie Pearce-Stevenson and leaving her body in the Belanglo State Forest in 2008.

Her remains were found in 2010 and she was identified using DNA.

Five days after killing her, Holdom murdered Ms Pearce-Stevenson's daughter Khandalyce near Wagga Wagga. The child's remains were found in a suitcase dumped on a remote highway in South Australia in 2015.

Holdom sat quietly in the dock of the Supreme Court looking around the public gallery.

The court was presented victim impact statements prepared by family members of Ms Pearce-Stevenson.

Her father Bruce Pearce's statement described how the death of his daughter still haunts him.

The court heard Daniel James Holdom's crimes were in "the worst category". ( ABC News )

Mr Pearce said he can't stop thinking about his daughter and never had the chance to meet his granddaughter.

"The anger, pain and hurt never goes away," the statement said.

"The hate that I feel is consuming … you have taken a daughter and granddaughter from our family."

Mr Pearce described nightmares about how the two victims died and fears justice will not be achieved.

Speaking of his grief and anger, he said no sentence will ever be enough for Holdom.

"I would like to see the death penalty for you … but even that would not be enough."

The worst category of murder

Former NSW Senior Crown Prosecutor Mark Tedeschi told the court Ms Pearce-Stevenson was murdered by someone she was in a romantic relationship with and who she should have been able to trust.

He said she was away from her family in isolated bushland when she died and after the murders Holdom raided her bank accounts.

Mr Tedeschi said Holdom also took "trophy" photos of Ms Pearce-Stevenson's body.

"Karlie's murder falls into the worst category of murders," he said.

Police made a public appeal for information about Ms Pearce-Stevenson and her daughter. ( AAP: Dean Lewins )

The court has previously heard that the mother and daughter were originally from the Northern Territory and Ms Pearce-Stevenson moved away from her family around 2006.

She was last seen leaving a home in Canberra with Holdom on December 14, 2008.

Earlier this year, Holdom entered a late guilty plea to two counts of murder a week before he was due to stand trial.

Mr Tedeschi called on Justice Robert Hulme to give Holdom a life sentence.

Holdom will be sentenced at a later date.