The girlfriend of the 16-year-old boy accused of stabbing a Queanbeyan service station attendant to death pulled a knife on her family after being told not to eat ice cream, a court has heard.
Police say the 14-year-old girl pulled out an 8-inch carving knife in the kitchen of her home the day after her boyfriend's alleged rampage, held it in a stabbing grip, and looked intent on attacking her uncle after he told her not to eat ice cream before her family went out.
Her grandmother feared the girl would harm her family after the recent stabbing in Queanbeyan and called police, the court was told.
The girl's defence lawyer told Queanbeyan Children's Court on Monday the teen's "emotions were running high" on Saturday and "she wasn't in a very good state of mind" as she was "caught up with" the teenager charged over the alleged murder.
"She was obviously a troubled young child," he said.
"Difficult circumstances" following the alleged rampage on Thursday and Friday may have contributed to her actions the next day, the court heard.
Her grandmother, protected by an apprehended violence order (AVO) police say the girl breached in the incident, was in the court supporting her granddaughter.
The teen is yet to plea to charges including damaging property, two counts of intimidation intending fear physical harm, and contravening an AVO.
Magistrate Michael Antrum refused bail after the police prosecutor argued she was a risk to people in the community.
"She poses far too great a risk and a threat to other members of her family," the prosecutor said.
A statement of facts he tendered to the court said police were concerned about the timing of the girl's actions following her boyfriend's alleged rampage.
She was at home on Saturday when she became upset on being told by her grandmother to delete an inappropriate Facebook post, according to police.
At 5.30pm the teen allegedly stormed off to the kitchen screaming when her sister didn't let her speak to her father on the phone, pounding an indentation in a gyprock wall on the way.
She began to open and slam shut doors and the fridge in the kitchen. Her uncle told her not to eat ice cream before the family went out soon, police said.
He and his father each held up a dining chair to create a barrier protecting them against the girl when she pulled out a knife, it is alleged.
Magistrate Antrum adjourned the case for plea until April 26.