Charlise Mutten was fond of her alleged killer and was excited to be spending Christmas with him and her mother before the fatal visit, a trial has been told.

Justin Laurens Stein, 33, has denied murdering the schoolgirl on or around January 12, 2022, at Mount Wilson, in the Blue Mountains west of Sydney.

The nine-year-old had been visiting Stein and her mother, Kallista Mutten, over the holiday break, with the group spending time between a property at Mount Wilson and a caravan at the Riverview Ski Park, about 90 minutes away.

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Charlise Mutten dies, Justin Stein charged with murder

Charlise's grandfather, Clinton Mutten, appeared as the Crown's first witness in the NSW Supreme Court trial on Tuesday.

She had lived with her grandparents from about the age of four after it became clear her mother, who was a long-term drug user, was unable to properly care for her, the jury heard.

Clinton Mutten said his daughter's drug use became worse during her relationship with Charlise's biological father, a union that was marred by domestic violence and ended soon after the girl's birth.

Charlise had "really liked" Stein and on one occasion asked if he thought the accused murderer would be a good dad, Mutten said.

He said she was "happy and excited" about the trip and he was not concerned for her safety despite the couple's history of drug use.

Stein's lawyer, Carolyn Davenport SC, suggested that at the time of Charlise's visit, her mother was continuing to use the drug ice intravenously.

But Charlise's grandfather said he was under the impression both had "cleaned their act up".

The trial heard from multiple witnesses who recalled seeing Charlise, Kallista Mutten and Stein at various times in the caravan park in the days before the young girl went missing.

Caravan owner Rodney Burns said a woman he did not know matching Kallista Mutten's description approached him on January 9 asking if he could buy her cigarettes and a soft drink while he was in town.

Burns said the woman spoke erratically, telling him her fiance had gone to the mountains and she did not have anything to eat or drink.

"She spoke very quick and all over the place," he told the court.

"The conversation just jumped everywhere. I got the opinion she was on drugs."

Kallista Mutten was sentenced to 12 months in prison for breaking and entering with the magistrate allowing her to spend this in the community under an intensive corrections order.

During his evidence, Clinton Mutten described his granddaughter as an academic all-rounder who loved animals and had dreams of becoming a veterinarian.

"I took her to school, I was the one who sat down at the parent-teacher interviews," he said.

"I was very much involved with Charlise."

Mutten said his daughter had maintained a "very strong" relationship with the nine-year-old despite their distance and would contact her regularly.

"She would look forward to communicating with her," he said.

"It was always there and it was unconditional."

The nine-year-old travelled from the Gold Coast to Sydney in December 2021 with plans to spend Christmas and New Year's Eve with her mother and Stein.

Charlise was reported missing by her mother on January 14.

On the evening of January 12, Charlise was taken back to Mount Wilson by Stein alone, while Kallista Mutten remained at the caravan, prosecutors said.

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CCTV of a ute towing a boat has been released as police continue their investigation into the alleged murder of Charlise Mutten, whose body was found in a barrel by a NSW river.

CCTV images captured the 33-year-old at a BP service station at Marsden Park, in northwest Sydney, the next day.

He was towing a boat with his Holden Colorado ute, which was also allegedly transporting a barrel containing Charlise's body.

The barrel was found wedged in a tree near the Colo River, northwest of Sydney, on January 18, four days after Charlise was reported missing.

She had been shot once in the head and once in the lower back.

The trial is expected to go for six weeks.