Kallista Mutten became distraught when confronted with details of her daughter Charlise's shooting and tearfully rejected a suggestion she was the one who pulled the trigger.
Justin Stein, 33, has pleaded not guilty to murdering the nine-year-old, instead claiming he witnessed Ms Mutten shoot the schoolgirl.
Charlise's body was found by police in a barrel by the Colo River the the Blue Mountains on January 18, 2022 with gunshot wounds to her face and back.
At the time, Ms Mutten was in a relationship with Stein and his trial heard the pair had plans to get married.
Stein's lawyer, Carolyn Davenport SC, suggested to Ms Mutten she was the one who fatally shot Charlise behind a chicken shed at the Blue Mountains property where she was staying with Stein.
"What I suggest is ... you had, in fact, shot and killed your daughter," Ms Davenport said in the NSW Supreme Court on Tuesday.
"Are you serious? ... no," Ms Mutten said.
"You shot her once in the back and once in the head," Ms Davenport said.
"I didn't even know where she was shot, so now I know," a distraught Ms Mutten replied.
At that point the court adjourned to allow Ms Mutten to compose herself.
Charlise, who lived with her grandparents on the Gold Coast, had been visiting her mother and Stein over the Christmas holidays.
During the visit, the group spent their time between a Mount Wilson property owned by Stein's mother and a caravan at the Riviera Ski Park, about a 90-minute drive away.
Ms Mutten claims the last time she saw her daughter was on January 11, when the nine-year-old travelled alone to spend the night with Stein at Mount Wilson while she remained at the caravan park.
Ms Davenport put to her she had seen Charlise alive on January 12 and the girl had travelled with her and Stein to Sydney, which she denied.
The defence barrister suggested Ms Mutten had shot Charlise after returning to the Blue Mountains property that evening and later placed the girl's body in a barrel on the back of Stein's ute without his knowledge.
"What I suggest is that at some stage, you managed to speak to him and told him that he had Charlise's body on the back of his (ute)," Ms Davenport said.
"No," Ms Mutten replied.
She admitted lying to police about Stein's drug use and access to firearms during an interview on January 21, three days after her daughter's body was discovered.
She said Stein had said not to reveal the truth about their drug use, including his consumption of methamphetamine.
Ms Davenport questioned why she would lie for Stein at a time when she knew Charlise's body had been found and he had been charged with her murder.
"I loved him," Ms Mutten replied.
"Even though you were told that he had been arrested and charged with the murder of your child?" Ms Davenport questioned.
"In my heart I really did believe that Justin had gone to look for her," an emotional Ms Mutten explained.
"I believed his side of the story."
Ms Mutten admitted using drugs during Charlise's visit but denied using them in front of her daughter.
She also admitted sometimes using a pendulum to help guide her decisions, but denied having a belief in the occult - or what Ms Davenport referred to as "witchcraft-type things".
"I wouldn't say witchcraft, it's spiritual," Ms Mutten said.
She said she believed in a "higher power", but denied receiving messages that told her to kill her daughter.
The trial continues on Wednesday.
