Teenager Adam Morrell died from head injuries and strangulation after being beaten and tortured for at least three hours, the trial in Nottingham was told.
Adam suffered 280 injuries
A pathologist said the 14-year-old suffered a total of 280 injuries.
One of the defendants told police he looked "like an alien" after being kicked like a football.
Another said he was completely unrecognisable.
Finally, the music was turned up at the house in Loughborough to cover the sound of his body being sawn into pieces.
Three days after the schoolboy's death, a group walking by the Grand Union Canal in the town found a black plastic bag wrapped in silver tape, floating in the water.
When they fished out the package, they saw what looked like fingers.
The bag was found to contain a severed arm.
Other body parts turned up around Loughborough over the next few days.
A woman found legs in another plastic bag.
A bag of clothes was discovered by police at an electricity sub-station.
Adam was tortured in a house on Havelock Street
The boy's head was found by police divers at the bottom of the canal.
The last Adam's family had heard from him was when he phoned his father, days before his death, to say he was staying with friends.
Those friends were: Matthew Welsh, 19; Welsh's girlfriend Sarah Morris, 17; former soldier Daniel Biggs, 19; and Nathan Barnett, 27.
On Wednesday, 19-year-old Matthew Welsh was convicted of murdering the schoolboy, while his girlfriend Sarah Morris was found guilty of assaulting the youngster.
Another teenager, Daniel Biggs, 19, was cleared by the jury of murder or of any part in the assault.
Nathan Barnett pleaded guilty to manslaughter on the grounds of diminished responsibility.
Welsh, the son of a Burton on Trent policeman, had told Leicestershire Police that they were drinking beer and whisky, smoking cannabis and taking ecstasy at the house in Havelock Street on the evening of 14 November, 2002.
Welsh said events took a turn for the worse when Adam threatened to tell police about their drug use.
The court had been told that all four of them kicked and attacked Adam.
He curled up in a ball and wept as he was savagely beaten.
Some of Adam's body parts were found in a canal
Welsh told police that Barnett had later scalded Adam with a combination of boiling water and sugar.
Barnett testified during the trial that Biggs helped him by putting his foot on Adam to squeeze the life out of the youngster.
He told a jury that he had played the children's game paper, scissors, stone with Biggs to decide who would kill Adam.
Biggs denied joining in the assault and said he had gone to a homeless persons' hostel.
He said Barnett, who pleaded guilty to manslaughter on the grounds of diminished responsibility, had killed Adam on his own.
All four pleaded guilty to conspiring to pervert the course of justice.
Sarah Morris told police she joined in the attack on Adam and said he looked "like an alien" after being kicked "like a football".
Morris said Adam had started moaning after a drink-and-drugs session and was told to shut up.
He was kicked because he was "bringing us down", she said.
The three others hit and kicked Adam and urged her to do the same, so she punched him in the head, chest and legs as well as in the face.
"The assault lasted about three hours, possibly slightly longer,"
Frances Oldham, defending Morris, said the teenage girl was the only member of the gang who had ever shown any remorse for what had happened.