An investigation is being launched over claims that police corruption helped shield the killers of black teenager Stephen Lawrence from conviction.
A BBC investigation alleges that the murder inquiry's Det Sgt John Davidson was paid by drug smuggler Clifford Norris, father of suspect David Norris.
The former detective denies any claims of corruption.
Neville Lawrence, whose son was stabbed in Eltham, south-east London, in 1993, said he always suspected corruption.
The Lawrence family has contacted the Independent Police Complaints Commission (IPCC) which has asked the Metropolitan Police to look into the latest claims before it can carry out any investigation.
Mr Lawrence told the BBC he hoped the case could be re-opened.
"We've always thought that there was something to do with corruption," he said.
"When they had the inquiry into Stephen's death, that wasn't in the remit so they didn't really get to look at it, so we were really disappointed," he told the BBC Radio 4's Today programme.
"I'm really pleased that this programme is actually showing some kind of proof that there was something like corruption that was more or less responsible for the case not being solved."
Mother Doreen Lawrence said: "I'm hoping that the IPCC will prove that they are independent, and so they investigate the corruption like how it should have been done a long time ago.
"It's taken us all this time to actually get here and to the fact that we knew that there was corruption all along but just couldn't prove it."
Home Secretary John Reid said he was sure the police would address any new issues raised by the documentary.
"The murder of Stephen Lawrence was a terrible, terrible crime and it remains a source of extreme frustration for everyone, but particularly Stephen's family, that the perpetrators have not been brought to justice," he told the BBC.
Neil Acourt, his brother Jamie, David Norris, Gary Dobson and Luke Knight, were arrested but nobody has ever been convicted.
The Crown Prosecution Service says there is not enough evidence against them.
A second police investigation revealed them to be a gang of racists with an obsession with knives.
The original Metropolitan Police investigation which followed Stephen's death led to the Macpherson Inquiry which found the force was guilty of "institutional racism".
During that inquiry, Mr Davidson - who now runs a bar in Spain and is on a full police pension - was criticised for his abrupt manner and incompetence.
Neil Putnam - a former corrupt police detective turned whistleblower - has told a BBC investigation to be screened on Wednesday night that Clifford Norris was paying Mr Davidson to obstruct the case and to protect the suspects.
"Davidson told me that he was looking after Norris and that to me meant that he was protecting him, protecting his family against arrest and any conviction," Mr Putnam said.
"From my conversation that I had with John Davidson on that day, I would say that John Davidson was receiving cash from Clifford Norris by his expression that he was using it was, he was getting a little earner out of it - it was a good little earner.
"That, in my mind, was corrupt practices."
Police said they had not been aware of Mr Davidson's alleged relationship with Mr Norris.
But Mr Putnam claims he told them in 1998 and that they had "suppressed" the information "to protect the Metropolitan Police".
Met Police Deputy Assistant Commissioner John Yates, who was given the task of ridding the force of corruption, admitted he thought Mr Davidson was corrupt.
"From all the evidence I've seen, and the intelligence I've seen, I have no doubt he was corrupt," he said.
But he said there was no evidence to suggest the alleged relationship had been suppressed.
"To suggest that we would in any way try and hide references to it is simply ridiculous," he added.
The Lawrence family's lawyer, Michael Mansfield, told the BBC there should be a inquiry to find the documents detailing Mr Putnam's interviews with officers as an informant.
Mr Mansfield said he was confident there could be a resolution to the case in the courts.
"After 16 years, the Birmingham Six got a resolution of their miscarriage of justice... and I'm a firm believer that in the end there are people out there who know - it's on their consciences.
"If you know information, if you see something like this, you never forget it."
Police say they will open up a special incident room following the investigation by BBC reporter Mark Daly.
The programme tracked down almost every person who had any involvement in the case - more than 100 people in total. These included the main witnesses, the alibi witnesses, peripheral characters, police detectives and the suspects themselves.
The suspects were invited on to the programme to account for their movements on the night of Stephen's murder.
The programme twice sent letters to their homes but got no response, although some of the letters were returned saying "not at this address".
The programme makers say they had observed the suspects at the addresses to which the letters had been sent.
The Boys Who Killed Stephen Lawrence will be shown on Wednesday on BBC One at 2100 BST.