Mistakes made by scientists during the original inquiry into Damilola Taylor's murder were "extremely regrettable human errors", a report has said.
Damilola died of a stab wound to the leg
But there were "no systemic failures" by the Forensic Science Service in its analysis of clothing, it concluded.
Danny and Rickie Preddie are serving eight-year terms for the manslaughter of Damilola, 10, who died in 2000 after being stabbed in Peckham, south London.
His parents said they were "enormously disappointed" by the findings.
In a statement read on behalf of Richard and Gloria Taylor they called for those responsible for the "dreadful errors" to be brought to account.
"Those fatal errors resulted in years of delay and pain for the family in their search for justice for Damilola," the statement said.
"The basic mistakes that were made by the forensic experts had catastrophic effects."
They said the report and its recommendations fell well short of expectations and called for an overhaul of the quality of forensic science used in court.
The Forensic Science Service (FSS) initially failed to identify blood spots on trainers and jumpers belonging to the Preddie brothers, who were convicted at a third trial into Damilola's killing.
Home Office Minister Joan Ryan said in a written ministerial statement the report made a number of recommendations to which she will give her full consideration.
"I would also like to express my sincere apologies to Damilola Taylor's family and acknowledge the further distress this has undoubtedly caused them," she added.
The report concludes: "There was no systemic failure in the operations of the FSS.
"There were however human failures in implementing the operating procedures of the FSS which brought about the failure to recover crucial evidence.
"That evidence was Damilola's blood on the right trainer said to belong to Danny Preddie and Damilola's blood on a black Giorgio sweatshirt said to belong to Rickie Preddie."
The report found mistakes were made by three FSS scientists, which it did not name.
The report's recommendations include establishing a forensic science service regulator.
It also said a complete second scientific examination of an article should be considered as an option.
In the first trial in 2002 four teenage boys had charges against them dropped or were found not guilty.
The Preddie brothers were jailed for eight years
In November 2003 all the evidence was reviewed and it was then the blood and fluid samples were re-tested by a private company the Forensic Alliance.
As a result, in 2006 Hassan Jihad and the Preddie bothers went on trial charged with Damilola's murder.
Mr Jihad was cleared in April 2006, at the age of 20, and the Preddie brothers were found not guilty of murder, but the jury could not reach a verdict on the manslaughter charges.
At a third trial later in 2006, the Preddies were convicted of Damilola's manslaughter.