Kriss Donald was described in court as a defenceless, young, slightly built schoolboy who experienced "extreme terror" before he died.
Kriss Donald's body was found in the east end of Glasgow
The 15-year-old was walking with friend Jamie Wallace in the Pollokshields area of Glasgow when they were set upon by Daanish Zahid and three others.
Mr Wallace, 20, told the court that Kriss was bundled into a car after they were attacked in March.
The teenager was later beaten, stabbed 13 times and set on fire.
Forensic expert Anne Ramage told the court that he may still have been alive when he was doused in petrol and set alight.
Ms Ramage said her examination of the area suggested the 15-year-old tried to extinguish the flames by rolling in a muddy hollow.
Forensic pathologist Dr Marjorie Black added that Kriss may have been held down over a log while he was knifed.
Dr Black said the schoolboy suffered seven stab wounds on his front, five on his back and one on his left arm during the attack.
She added that he was likely to have been restrained by "at least" one person.
The brutal attack took place behind the Celtic Supporters Club on London Road, in the east end of the city.