A teenager who was allegedly stabbed with a pen in court by a member of his victim’s family has been sentenced to more than a decade behind bars.

The 18-year-old defendant, who cannot be named as he was aged 17 years and eight months at the time of the offence, pleaded guilty in Brisbane Supreme Court on Monday to the murder of 19-year-old man Abddullahi Ahmed lyow.

The teen stabbed Iyow three times in the abdomen with a large hunting knife on the side of the road in the southern Brisbane suburb of Acacia Ridge at 2.30pm on May 17, 2024.

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Iyow died in hospital 33 days later from infection and organ failure.

Justice Rebecca Treston said the teen had stabbed his friend in “virtually unprovoked circumstances” after an altercation in which Iyow broke his phone.

“It could hardly be considered to have provoked your response. (The victim) was on the ground when you repeatedly stabbed him,” she said.

“You inflicted violence when the victim did not fight back.”

The teen had complained that he would lose his drug dealing contacts as a result of damage to his phone.

Treston told the teen he had taken the life of a joyful young man and left his family with a devastating loss.

She said she took the events of Monday last week into account, when the defendant was allegedly assaulted in court by someone related to lyow.

The teen was due to face sentencing that day when a 22-year-old man allegedly stabbed him with a pen in the back before being restrained by court security.

In-court security has since been tightened.

Only some of the victim’s family members returned on Monday.

The teen also pleaded guilty to possession of a knife in a public place and threatening violence.

He also threatened a nearby resident who tried to break up the fight with Iyow.

Treston said the teen had been diagnosed with severe conduct disorder and antisocial traits.

He had arrived in Australia as a seven-year-old after his family fled war-torn Somalia.

He started using substances and alcohol from grade 7 at school and was soon selling drugs and immersed in gang culture.

The teen was isolated and not attending school or employment at the time of the murder.

Treston said the teen later told a psychiatrist he “found stabbing people enjoyable”.

“The protection of the community is a matter of great significance in a case like this,” Treston said.

She said she had no option but to regard the teen’s offending as particularly heinous, with a sentence of up to 14 years.

“Context of gang violence and prevalence of knife offences leading to needless deaths calls for significant punishment,” she said.

The teen will be required to serve 70 per cent of his 12 years in detention.

Upon release, his refugee visa could also be cancelled.

The 22-year-old man accused of assaulting the teen in court is due to face Brisbane Magistrates Court on April 10.