Scotland Yard is being pressured to re-examine its files on the drug-baron father of one of the main suspects in the killing of Stephen Lawrence.

The move follows the screening of a BBC documentary that claimed Clifford Norris, whose son David was arrested in connection with the stabbing of the black teenager, paid an officer on the murder inquiry team to protect his family from arrest.

The Metropolitan Police have been dismissive of the corruption allegations against Detective Sergeant John Davidson, who the programme claimed effectively prevented Stephen's killers from being prosecuted. But it has set up a new witness hotline in the hope of obtaining fresh evidence from the public.

Now Michael Mansfield QC, the Lawrence family barrister, is demanding that the force "go back to the beginning" on the case and investigate if other officers were in the pay of Norris.

He wants them to examine files dating back more than 18 years, covering the period from 1988 to 1995 when he managed to evade capture. Norris was eventually prosecuted for conspiring to import drugs and possessing a loaded firearm.

The leading human rights barrister said: "The Met has to go back to the beginning on this. Twenty-four hours after the murder [of Stephen Lawrence] a man came forward and named the main suspect, yet nothing was done. If this has happened once then it may not have been for the first time. They must check if other investigations were carried out properly."

No one has ever been brought to justice for Stephen's murder 13 years ago. David Norris was one of five white youths who were identified as suspects in the brutal race killing, but denied any involvement. Known as "the Firm", their presence is still felt in Eltham, south-east London, where the murder took place. Although they have moved out of the area, they still visit their old haunts including Bill's Caf?, which is on the same street where the stabbing took place.

A member of staff at the caf?, who asked not to be named, said: "They still come in here but not usually together. They never talk about it here; they just keep their heads down."

Racist attacks are still worryingly common in the area. Earlier this month, a young Asian boy ended up in hospital after being attacked in McDonald's. The crime was captured on CCTV but no one has been charged.

Gangs such as Kill the Niggers, Racist Criminals and Racist Attackers are the new names that strike fear in the community. They have been linked to the kidnapping of teenagers, intimidation, protection rackets and attacks by thugs.