The exact circumstances of schoolgirl Charlise Mutten’s final moments alive may never be known.

The nine-year-old’s body was found dumped in a barrel by the Colo River in the NSW Blue Mountains on January 18, 2022.

She had two gunshot wounds – likely delivered at close range – to her back and head, a murder trial in the NSW Supreme Court has been told.

Prosecutors allege Charlise was fatally shot having gone to spend the night alone with her mother’s partner, Justin Stein, leading in part to police charging the 33-year-old with her murder.

However, Stein has never wavered in his denial that he killed Charlise, accusing her mother Kallista Mutten of pulling the trigger – a claim she vehemently rejected in court.

Charlise had been visiting Stein and her mother over the Christmas holidays from the Gold Coast, where she lived with her grandparents.

The group spent their time between a sprawling Mount Wilson estate owned by Stein’s mother in the Blue Mountains, and a caravan at the Riviera Ski Park, about a 90-minute drive away.

Both Stein and Ms Mutten have histories of crime, drug use and mental illness, with Stein’s barrister Carolyn Davenport SC describing the pair as “damaged”.

Despite this, photos and accounts of those who saw Charlise during that time, suggested she was happy and enjoying a rare holiday with her mother and Stein, with whom the court heard she had a close relationship.

On January 11, Ms Mutten stayed at the caravan by herself while Charlise spent the night with Stein at Mount Wilson, asking her mother “can I go with daddy?”, the trial was told.

Ms Mutten claims it was the last time she saw her daughter.

Prosecutors alleged that at sometime that evening or the following morning, Stein shot the girl after drugging her with his own antipsychotic medication, which according to expert evidence would have acted as a profound sedative on a child her age.

Toxicology revealed traces of the drug in the girl’s system, for which Stein had no explanation.

Having allegedly killed Charlise, the trial was told Stein spun a story to Ms Mutten, about the girl being sick and having left her in the care of a woman who had come to value items at the Mount Wilson estate.

It was agreed Stein picked Ms Mutten up from the caravan that morning, and they travelled together to Surry Hills in Sydney where they bought drugs, returning to Mount Wilson shortly before 9pm.

Prosecutors allege at that point Charlise was dead, but Stein claims she was alive and went with the pair to Sydney, concealed from view in the back seat of the ute.

According to his version, within a 20-minute window when they got back to Mount Wilson that evening, Ms Mutten shot Charlise, afterwards screaming at him “you did this”.

After witnessing Ms Mutten shoot her daughter, Stein said he went back to the house, cried, rolled himself a joint and went to sleep.

It is an account crown prosecutor Ken McKay SC described as “nonsense”.

He pointed to facts including Ms Mutten having placed calls to the Mount Wilson landline during the day, and later calling two children’s hospitals, as evidence Charlise was not with them during the day and a later a belief by Ms Mutten that her daughter was missing.

Stein also initially told police the same version of events about leaving Charlise with the auctioneer, but after being pressed by officers admitted the story was fabricated and instead implicated Ms Mutten as the shooter and mastermind of the auctioneer story.

He explained text messages suggesting he was searching for Charlise, when prosecutors allege he was looking to dump her body, were part of the ruse concocted by Ms Mutten.

In disturbing images for which the case will likely be remembered, Stein was captured on CCTV towing a boat behind his ute with Charlise’s body in a barrel on the back.

During that journey he travelled to at least three boat ramps across Sydney over several hours.

Earlier, the unemployed heroin addict was recorded buying bags of sand at Bunnings, which would later be found in the barrel with the girl.

Police would later locate Charlise’s body using data from Stein’s phone which led them to the exact location of the barrel.

His finger prints were on a rifle found buried on a fire trail near the property, that prosecutors alleged was the murder weapon.

But according to Stein he had intended to store the boat at the Riviera caravan, and had purchased the sand to fix a patio there.

He said he had been driving the ute when he discovered Charlise’s body in the back, causing him to panic and dump her body.

The 12 jurors who heard nearly four weeks of evidence have yet to deliver a verdict but will return on Tuesday to resume their deliberations.