The mother of murdered London teenager Stephen Lawrence wants the Home Office to reopen an inquiry into police handling of the case.
Doreen Lawrence has written to the Home Secretary about her concerns that the initial 1993 investigation involved corrupt police.
Gary Dobson and David Norris were convicted of the murder in January, 18 years after the fatal stabbing.
A previous inquiry concluded there was no evidence of corruption.
Stephen Lawrence was 18 when he was stabbed to death near a bus stop in Eltham, south east London, in April 1993.
Mrs Lawrence told the BBC: "Back then we had serious concerns about how the inquiry was run because each time we had information, particularly about the individual we believed was responsible for Stephen's murder, the police took no action. We kept wondering why."
She said: "I would like the home secretary to have another public inquiry into the corruption.
Why wasn't Macpherson [inquiry into the case] given all the information it should have been given."
The Macpherson Inquiry, in 1999, was asked to identify lessons learned which would help with the investigation and prosecution of racially motivated crimes. It also examined the Lawrences' allegations of corruption.
If [police] they have any fresh evidence that police corruption may have hampered the original murder investigation, they should refer it to us.”
End Quote Independent Police Complaints Commission
It concluded: "It is right that we should say at once that no collusion or corruption is proved to have infected the investigation of Stephen Lawrence's murder."
But Sir William Macpherson's adviser, Dr Richard Stone, told the BBC this did not mean there was no evidence, just that it was not conclusive.
And in October 2007, the Independent Police Complaints Commission carried out a year-long inquiry into claims that the first police inquiry into the murder was hindered by a corrupt officer.
The claims were made in a BBC programme in July 2006, which reported former police detective Neil Putnam saying that Det Sgt John Davidson took a bribe from Clifford Norris, father of David Norris.
The IPCC decided the claims were unfounded.
However, in another police corruption trial at the Old Bailey last year, Mr Putnam repeated the allegation, under oath.
He said he had been talking to Mr Davidson about the Lawrence murder suspects.
He told the court: "I felt that it was obvious that the boys were guilty, so obvious something's wrong. And then John suddenly came out with the fact that he'd been dealing with, his exact words were, 'old man Norris'."
Mr Davidson, who now lives in Spain, has so far not responded to attempts to contact him.
He has always denied being corrupt.
Renewed allegations about corruption also surfaced last week in the Independent newspaper.
'No further investigation'
The Met Police assessed the Independent's article and said: "This assessment does not suggest there is evidence that requires further investigation that has not previously been undertaken by the MPS, the IPCC or the Macpherson Inquiry.
"However, the MPS does want to meet the Independent journalists to better understand what they consider is new evidence before any final decision is made. The process of officers contacting the Independent is under way."
The IPCC said: "We have always made clear to the Metropolitan Police, and we have reiterated this in light of recent reports, that if they have any fresh evidence that police corruption may have hampered the original murder investigation, they should refer it to us."