Two 14-year-olds congratulated each other as they ran away after teenager Angus Beaumont was fatally stabbed north of Brisbane, a court has heard.
Angus was 15 when he died after a knife was thrust 14cm into his chest in an altercation with the two teens at Redcliffe in March 2020, crown prosecutor Chris Cook said.
The two 14-year-olds - who can't be named - had earlier bought cannabis off a "wannabe drug dealer" who was in a group of teens that included Angus at a Redcliffe skate park that night, the court heard.
The pair were armed with knives when they pursued Angus' group on foot a short time later in a bid to steal the remainder of their drugs, Mr Cook said.
Angus was wearing knuckle dusters and was handed a knife by another member of his group before confronting the two 14-year-olds, telling them to "f*** off", the court heard.
CCTV footage was shown in Supreme Court of two teens fighting the taller Angus at the same time, including the fatal blow which went "through his heart".
The two 14-year-olds can be seen making contact with their hands before running away.
"Moments after (the teenager) ... stabs Angus Beaumont ...his mate slaps his hand...they congratulate each other and then they are off," Mr Cook told the jury.
After being struck in the chest, Angus is seen in the footage falling as a teen attempts another strike.
The year 10 student hit the ground so hard he had abrasions to his head, the court heard.
"He decided to take a stand to get the defendants away. Angus was not the one who initially raised his knife - this was not a consensual knife fight," Mr Cook said.
"He didn't charge at them with his knife. He was just wanting them to go away.
"By the time he raised his hand that had the knife in it ... for the first time ...(one of the teenagers) had already pounced."
The weapon was never recovered, but the 14cm depth of the wound suggested it was "bigger than your average steak knife" and was described as a "hunting knife" by a witness, Mr Cook said.
One of the 14-year-olds suggested in police interview audio played in court that they had been ripped off in the cannabis deal.
But Mr Cook said they had paid $25 for 1.5 grams of cannabis and had received 1.8 grams instead.
"This was not a drug deal gone wrong. This was a drug deal gone right but that wasn't good enough for ...(two 14-year-olds). The only reason they had to chase (Angus' group) ... was to rob them of more drugs," he said.
"They ... (two teens) were the aggressors that night ... they killed him (Angus)."
The two teens have pleaded not guilty to murder.
The trial before Justice David Jackson continues.
