Minimum jail term is 12 years because pair were juveniles, and law was less tough on racist crimes in 1993

Gary Dobson and David Norris, the two men convicted of the racist murder of Stephen Lawrence, will be sentenced today.

The pair, who were 17 and 16 at the time of the murder, will receive a sentence that takes into account as a starting point the fact that they were juveniles at the time of the fatal stabbing.

But Mr Justice Treacy, the trial judge, will also take aggravating factors into account: specifically that the murder was racist, and also that the pair realised one of their group might use a knife.

Had they committed the crime in the last year, Dobson and Norris would expect to receive much tougher sentences, with minimum terms of 25 years for a racially aggravated knife murder.

But under the law at the time of the Lawrence murder, juveniles received lesser sentences for such crimes. The starting point for Dobson's and Norris's sentences is a minimum term of 12 years because they were 17 and 16 at the time of the attack.

But Dobson and Norris could receive sentences of around 18 years, if the judge takes into account all the aggravating factors available.

Dobson and Norris were convicted by an Old Bailey juryon Tuesday, 18 years and eight months after Lawrence was attacked as he waited for a bus in Eltham, south-east London.

The 18-year-old A-level student was engulfed by a gang of five or six white youths, who stabbed him twice in the upper torso, severing two arteries.

His parents spoke of their mixed feelings at the verdict, with Lawrence's mother, Doreen, saying the occasion was not one for celebration.

Speaking outside the Old Bailey, she blamed the police for putting her through 18 years of uncertainty and grief because they had failed to do their job properly in the first place.

"Despite these verdicts, today is not a cause for celebration," she said. "How can I celebrate when my son lies buried, when I cannot see him or speak to him?

"When I will not see him grow up or go to university, or get married or have children. These verdicts will not bring my son back.

"How can I celebrate when I know that this day could have come 18 years ago if the police, who were meant to find my son's killers, [had not] failed so miserably to do so?"

Neville Lawrence said five or six men were responsible for killing his son, and he did not think he could rest until they had all been brought to justice.

The police inquiry into the Lawrence murder remains open, and detectives have nine remaining suspects for the killing. Among these are the Acourt brothers, Neil and Jamie, and Luke Knight ? who were named as prime suspects in the Macpherson report into the killing.

But after seven police investigations costing ?30m and the latest review by forensic scientists, no new evidence has emerged against the remaining suspects.

Detectives believe their only hope in bringing anyone else to justice is a change of allegiances. They will visit Dobson and Norris in prison in an attempt to persuade them to talk, after 18 years in which they have maintained a pact of silence.

But the acting deputy commissioner of the Metropolitan police, Cressida Dick, who ordered the 2006 cold case review that led to the convictions, said there were currently no "live" lines of inquiry.

"If there was an opportunity to bring the other people who were involved in that night to justice, we would do so," she said.

Speaking last night on Channel 4 News, Neville Lawrence called for Norris and Dobson to name the rest of those responsible for his son's murder.

"I'm praying that these people now realise that they have been found out and say to themselves: 'Yes I did that awful deed, but I wasn't alone in that action that night and there are other people who are also guilty of what I have done' and name them," he said.

Neil Acourt, Jamie Acourt and Luke Knight were arrested along with Norris and Dobson in 1993 in connection with the murder.

Dobson and Norris were convicted after scientists discovered a minute spot of Stephen's blood embedded into the weave of the collar of Dobson's jacket. They also found tiny fibres from Stephen's clothes on items seized from the homes of Dobson and Norris. On a pair of jeans belonging to Norris, they also discovered a tiny hair, which after mitochondrial DNA testing was found to match the Lawrence family maternal line.

Scientists recovered the material using advanced techniques that were not available to the original case scientists.

Dobson and Norris denied the murder. They said their clothing had been contaminated as police mixed up evidence over the years. Detectives spent months establishing the movements and handling of the exhibits since 1993 ? and the jury were told contamination was implausible.

The jury deliberated for just over eight hours before announcing their verdict yesterday. As they did so, Dobson shook his head. He stared at the jury and said: "You have condemned an innocent man. I hope you can all live with yourselves."