Two men have finally been convicted of the racist murder of Stephen Lawrence, 18 years after a white gang fuelled by hatred stabbed the black teenager to death.

Gary Dobson, 36, and David Norris, 35, were found guilty of murder on Tuesday by a jury at the Old Bailey. The crime had raised searching questions about racism in Britain.

The verdicts were delivered in a silent courtroom after the judge ordered

everyone to remain quiet. Dobson shook his head as the guilty verdict was announced. Norris stared ahead.

As he was led away to the cells, Dobson looked at the press bench and the jury and said: "You have condemned an innocent man here today I hope you can all live with it."

In the public gallery his mother, Pauline Dobson was heard sobbing. As she walked away she said: "This is so wrong. He did not kill that man – he is innocent."

Stephen Lawrence's father, Neville Lawrence, was in tears. Doreen Lawrence, seated near him, was also crying.

Mrs Lawrence was critical of the original Scotland Yard investigation into Stephen's death in 1993, saying: "Had the police done their job properly, I would have spent the last 18 years grieving for my son rather than fighting to get his killers to court."

Neville Lawrence said he was "full of joy and relief that two of my son's killers had been convicted" as a statement was read out by his solicitors. Mr Lawrence said he was conscious there were five or six attackers that night and that he didn't think he would "be able to rest until they are brought to justice".

The judge, Mr Justice Treacy, said he would sentence both men tomorrow.

Stephen Lawrence was stabbed to death 18 years ago.

The pair were part of a group of five white men who were suspected just hours after the murder in 1993, but had escaped justice through police failings and because some witnesses were too scared to come forward.

New scientific evidence tied Dobson and Norris to the murder and exposed as lies their claims that they were not present when Lawrence was attacked. A covert video shot in the flat that Dobson rented in 1994 showed him and Norris bragging and fantasising about inflicting violence on ethnic minorities, using explicit racist language, and having close friends who handled knives.

The case was one of the most famous unsolved murders in Britain. An 18-year fight for justice by Lawrence's parents led to a public inquiry which uncovered blunders by the Metropolitan police, blamed on institutional racism, which allowed his killers to escape justice.

Lawrence, 18, was murdered on 22 April 1993, as he and a friend waited for a bus in Eltham, south-east London.

They were attacked by a group of five to six white youths who shouted: "What, what, nigger?" and then rushed towards them.

The jury heard that Lawrence's friend, Duwayne Brooks, urged him to flee, shouting "get up and run, Steve". But by then Lawrence had been caught by the white group, which "swallowed" him up through its "weight of numbers".

Prosecutor Mark Ellison QC said "hand and leg movements" were seen by a witness as Lawrence was attacked. He was stabbed twice, in his upper torso, with arteries being severed.

Ellison said: "Stephen Lawrence was likely to have been upright when wound one was inflicted, but may have been lying on the ground by the time he was stabbed in the left shoulder."

The group fled, the jury heard, leaving Lawrence dying on the pavement. Despite efforts to save him, he was pronounced dead by midnight. His death was caused by the loss of blood from stab wounds.

Ellison said: "The only discernible reason for the attack was the colour of his skin. The way in which the attack was executed indicates that this group were a group of like-minded young white men who acted together and reacted together. They shared the same racial animosity and motivation."

Lawrence's parents, Doreen and Neville, had sat through much of the detailed evidence about their son's murder, which had begun in November. At times it seemed almost to overwhelm them.

The blunders from the first police investigation into the murder had for more than a decade appeared to have been so severe that Lawrence's killers would not face justice in court.

But new evidence was unearthed by a cold case review which used new techniques and more rigorous methods to examine clothing from the victim and from the five main suspects.

Scientists found that on Dobson's grey bomber jacket, in the weave of its collar, was a blood spot, measuring 0.5mm by 0.25mm. The chances of the blood coming from anyone other than Lawrence were one in a billion.

The re-examination also found that 16 fibres from three pieces of Lawrence's clothing were recovered from Dobson's jacket, or from the evidence bag it had been stored in.

Norris was tied to the murder by two hairs belonging to Lawrence that were found in the evidence bag containing jeans recovered from Norris's bedroom. Ellison told the jury: "Within the debris from the packaging of the exhibit … were two short, dark brown-coloured, cut hairs. They were 1mm and 2mm in length."

They were sent to the US for mitochondrial DNA testing, which focuses on the genetic makeup of hair cells. The technique had not been available in the mid-1990s. They were found to match Lawrence's DNA or that of a maternal relative to a certainty of 999 in 1,000.

Seven fibres were also found on Norris's blue sweatshirt that potentially came from two items of Lawrence's clothes.

Dobson and Norris took the stand in their own defence, after a covert video exposing their racism and propensity for violence was played to the jury.

It helped establish in the jury's minds that the pair were – at around the time of the murder at least – racist and violent.

Norris was recorded talking about "skinning" black people and setting them alight. Dobson was also recorded uttering racist remarks, and saying he had carried a Stanley knife and threatened to use it against a black man.

Norris said: "If I was going to kill myself, do you know what I would do? I would go and kill every black cunt, every Paki, every copper, every mug that I know."

Norris later says: "I would … I would go down Catford and places like that, I am telling you now, with two sub-machine guns and I am telling you I would take one of them, skin the black cunt alive, mate, torture him, set him alight … I would blow their two arms and legs off and say, 'Go on, you can swim home now.' They would be bobbing around like that."

Dobson is recorded discussing a man, calling him a "nigger" and threatening him with a Stanley knife.

Dobson is caught by the camera "walking about with [a] large knife", according to a transcript. Other extracts show him using the terms "Paki" and "nigger".

Testifying in his own defence, Dobson admitted lying to police when, in a 1993 interview, he told detectives he did not know Norris. For his part, Norris told the Old Bailey, he could not remember where he was on the night of the murder.

Dobson had previously been acquitted of the murder in 1996, after the Lawrences brought a private prosecution. In May this year, the court of appeal quashed his acquittal after deciding that the scientific evidence was sufficiently new and compelling.

Three other suspects remain free. Neil and Jamie Acourt and Luke Knight deny involvement in the murder.

Detectives hope that the long-awaited convictions will lead to new evidence emerging against the rest of the gang.

Dobson and Norris claimed that the scientific evidence against them came from contamination caused by failings in the way the exhibits had been stored over the last 18 years.

Tellingly, they did not produce a single expert to testify in support of their claims that contamination had somehow produced the evidence against them.