A 15-year-old girl who stabbed a snack bar owner in The Hague to death in January has been sentenced to one year’s youth detention and compulsory psychiatric treatment of up to seven years – the maximum sentence for a minor.

Her 17-year-old brother was sent to a juvenile prison for six months and another girl, also aged 17, was given 10 months for their role in the killing plus other crimes.

The snack bar owner, who was out walking with his wife, was kicked and punched by the gang before the girl stabbed him in the back. He died of his injuries in hospital.

A motive for the crime has not been established but the court said the conflict appears to have begun during the pandemic. The three were “looking for a confrontation with the couple” when the killing took place, the court said.

The public prosecution department said it was “shocking” how they discussed the killing with each other on the phone after their mobiles had been tapped.

“They have shown no remorse or insight into the suffering they have caused,” the court said, passing sentence.