The parents of a teenage boy who killed nine children and a security guard in a mass shooting at a school in Serbia last year have been jailed.

The boy's father, Vladimir Kecmanoviæ, was sentenced to 14-and-a-half years imprisonment on Monday, while his mother, Miljana Kecmanoviæ, was given a three-year prison sentence.

Nemanja Marinkovic, an instructor at the Partizan shooting club who taught the boy how to use a gun, received a sentence of one year and three months.

The boy, who has been held in a psychiatric institution since the May 2023 attack, cannot be put on trial because he is below the age of criminal responsibility.

However, his parents were accused of a "serious act against general safety" for failing to secure the weapons and ammunition properly. They denied the charges.

Their trial has been held behind closed doors.

At the high court in Belgrade on Monday, Vladimir was found guilty of endangering public safety by teaching his son to shoot and failing to secure his gun. He was also convicted of neglecting a minor.

Miljana was found guilty of neglecting a minor but acquitted of illegally possessing weapons and ammunition.

The boy, who has been identified only as KK, was brought to the court in October by a special escort, leaving the psychiatric hospital for the first time since the attack at Vladislav Ribnikar primary school.

He was questioned as a witness by the judge, the prosecutor and defence and lawyers for the families of the dead and wounded. He also answered questions from the mother of a murdered child.

Parents of the murdered children attended the hearing in the hope of shedding light on the motive for the boy's mass shooting.

A lawyer representing the families described it as "one of the most harrowing trials I have witnessed in my career".

KK was 13 when he took a handgun to the school and opened fire on other children. Eight of the nine children he murdered were girls.

Serbia was plunged into further grief less than 48 hours later, when another eight people were shot dead by a 21-year-old man in a village outside the capital.

Following his testimony at his parents' trial, the family's lawyer told reporters that the boy had lived a normal life before the shooting and no court process would be able to establish what had led to his attack.