A jury has begun deliberating in the alleged murder of Charlise Mutten after being told the issue in the case is not about how the schoolgirl died but who pulled the trigger.

Charlise’s body was found near the Colo River, north-west of Sydney, on January 18, 2022, with gunshot wounds to her face and lower back.

Justin Stein, 33, has pleaded not guilty to murdering Charlise, claiming it was the girl’s mother, Kallista Mutten, who shot the nine year old.

Justice Helen Wilson concluded her instructions and summation of the evidence in the NSW Supreme Court trial on Thursday and sent the jury to begin deliberations.

It could take the 12 men and women days or just hours to arrive at a unanimous verdict following a trial that has run for two weeks less than expected.

Stein admitted dumping Charlise’s body, but he said Mutten shot her daughter and placed her body in a barrel on the back of his ute without his knowledge.

Mutten denied any involvement in her daughter’s death and broke down in tears when faced with the accusation in court.

Many of the facts of the case were not in dispute, including that Charlise died from gunshot wounds she sustained at or near a Mount Wilson estate owned by Stein’s mother, the jury heard.

“The issue is not how Charlise died, it’s who pulled the trigger,” Wilson said.

The judge told jurors that if they found there was a reasonable possibility that Mutten shot her own daughter, they must find Stein not guilty.

“The Crown has no evidence of someone who saw the shooting of Charlise by the accused,” she said.

Stein appeared as the defence’s only witness in the trial, spending two days going over his version of events at the start of the week.

At the time of her death, Charlise had been visiting her mother and Stein from Queensland, where she lived with her grandparents.

The trio spent their time between the Mount Wilson property and a caravan at the Riviera Ski Park, about a 90-minute drive away, the trial was told.

Charlise spent the night of January 11 alone with Stein at Mount Wilson, while her mother remained at the caravan, which is when prosecutors argued he killed her.

Crown prosecutor Ken McKay SC said it was open for the jury to find Stein had drugged and fatally shot Charlise.

Toxicology revealed Charlise had traces in her body of the anti-psychotic drug Seroquel, for which Stein had a prescription to treat schizophrenia.

The jury heard an adult dose of the drug would have a profound sedating effect on a child.

McKay said a possible motive was that Stein killed Charlise when she became sick after he gave her the drug.

Stein denied giving Charlise the medication, instead claiming that she was shot by Mutten on the night of January 12.

He said he went along with a plan to cover up the murder, including lying to police about leaving the girl in the care of a woman who was valuing property at the Mount Wilson estate.

Stein claimed he was unaware Charlise’s body was in a barrel on the back of his ute until the next day and that he panicked and ultimately disposed of her remains when he found out.

-AAP