The killers of schoolboy Damilola Taylor were brought to justice today - six years and three trials after his death.
An Old Bailey jury took a day to convict the Preddie brothers - Ricky, 19, and Danny, 18 - of his manslaughter.
They were arrested a few days after 10-year-old Damilola bled to death after being cut with a broken bottle near his home in Peckham, south London, on November 27, 2000.
But vital leads were missed by a forensic laboratory and investigators.
The brothers, who were 12 and 13 at the time, were released without charge.
One was being monitored by the probation service at the time and the other was on bail and detained at a children's home.
They were re-arrested last year when a second forensic laboratory re-examined clothing seized at the time and discovered spots of Damilola's blood and fibres from his uniform.
The youths, also from Peckham, had denied the charge. They had been on conditional bail since April when they were cleared of murder and assault with intent to rob.
The jury could not agree on manslaughter and the six-week retrial began in June.
After today's verdicts were announced Ricky Preddie started shouting in the dock, accusing the jury of being corrupt.
He was surrounded by around a dozen prison officers as he become increasingly upset and continued shouting and swearing.
He shouted: "You are corrupt. You are nothing."
The judge, Mr Justice Goldring, said: "Take him down."
Ricky Preddie was taken out of court but his shouts could still be heard for some time.
Danny Preddie, who had been trying to calm his brother down, looked shocked as he sat back down to listen to the rest of the proceedings.
Damilola's father Richard Taylor looked calm as he heard the verdict and through the commotion which followed.
His mother Gloria looked down, one hand held to her cheek as the day she had waited for finally arrived.
Another defendant, Hassan Jihad, 20, from Peckham, was cleared of all charges following the three-month trial held in April.
Four other youths, all aged under 18, stood trial at the Old Bailey in 2002 and were cleared after the chief prosecution witness, a young girl codenamed Bromley, was labelled a liar.
The Preddies, who had reputations for violence and were prominent in a local gang, were in youth detention centres serving sentences for other offences when they were re-arrested.
They denied being involved in the attack on Damilola although the prosecution said there was "compelling evidence" against them.
The jury was told they had convictions for robbery, some at knifepoint, and witnesses claimed the brothers had confessed to the killing.
The brothers were implicated soon after Damilola's death with other suspects telling officers: "Ask the Preddies" when questioned.
A pal of Damilola, who cannot be named for legal reasons, told police he thought Danny Preddie may have come off worse in a fight with Damilola breaking his gold chain.
The youth, who is now 18, told the court that he once witnessed Danny asking Damilola if he had a cigarette - then taking a swing at him.
The attack on Damilola, who had come to Britain only a few months earlier from Nigeria, may have been a revenge attack involving Danny's older brother and his pals.
Damilola was surrounded by a gang of youths in Blakes Road, Peckham, as he made his way from an after-school club at Peckham library to his home on the run-down North Peckham Estate.
Someone broke a small, green beer bottle leaving a shard of glass which was used to "juk" Damilola in his left thigh.
The bullying act of cutting or jabbing with a twisting motion, was intended to hurt Damilola - but not to kill him.
Damilola, however, was a little boy and the sharp weapon cut through his flesh and blood vessels.
By the time he limped along the road and up two flights of a filthy stairwell, he was near death.
He was found slumped against a wall on a landing by carpenter Guillermo Casal who had following a trail of blood.
After collapsing into his arms, Damilola's last words were "I'm OK, I'm OK".
Today's convictions bring an end to the misery of Damilola's parents, Richard and Gloria, who were bewildered by the failure to identify their son's killers.
They said they were profoundly disappointed following the last inconclusive trial.
The Forensic Science Service, a Home Office agency at the time, is launching an inquiry into the slip-ups which were later picked up by the private science lab.
A drop of Damilola's blood was found on the heel of a trainer found in Danny's room and another drop was on a sweatshirt in Ricky's room.
There were a number of fibres on clothing but it emerged that the first lab would not have routinely checked for these unless requested to by a senior police officer.
Scotland Yard is re-examining a number of other cases to see if other vital forensic evidence could have been overlooked.
Victor Temple QC, prosecuting, told the court that, as Mr Casal waited for help, he looked down to the ground floor and noticed three youths in hooded jackets.
One made a cutting gesture on his left thigh to indicate where the wound was.
Damilola's mother found a police cordon when she went to look for him.
The following night, she was laying flowers at the spot with family members when the Ricky Preddie and another youth were seen going up the stairwell.
When they came down, the youth was not "his usual arrogant self", according a policeman guarding the spot.
Danny Preddie was on a 24-hour curfew at the Abbey Street children's home 1.8 miles away, but witnesses said he was adept at giving staff the slip.
A social worker said he had been assigned to watch him and he was no more than a few feet away from him during the time.
But he admitted he lost sight of him when the boy was in a girl's room during the afternoon.
A blood stain containing a broken fibre from the cut in Damilola's trousers was found on the upper heel of one of the boy's trainers, said Mr Temple.
A scientist said it was not there when she checked the shoe using chemicals, but the stain was clearly visible when a photograph taken of it at the time was later blown up.
Six burgundy fibres like those used in Damilola's school sweatshirt were found on Danny Preddie's black jacket and four on his blue hooded sweatshirt.
One blue fibre indistinguishable from those in the blue sweatshirt was found on Damilola's silver jacket.
Two red fibres were found on his brother's clothing. Ricky's black sweatshirt had a drop of Damilola's blood in the weave of the right cuff.
And fibres which could have come from his sweatshirt were found on Damilola's jacket.
Mr Temple said the failures in the case were due to "human error".
He said: "People make mistakes. Their failures do no more than reflect the frailty and vulnerability of human nature."
The failure to keep tabs on the youngest brother in the children's home had led to "catastrophic consequences" for Damilola and his family.
The cost of the investigations and court cases is estimated at £16 million.