Two white men were jailed on Wednesday for murdering a black teenager in London 1993, a landmark case which exposed the institutional racism of the capital's police in an official inquiry into the initial botched investigation.

Judge Colman Treacy ruled Gary Dobson should serve a minimum 15 years and two months and David Norris 14 years and three months for the murder of Stephen Lawrence at a bus stop, calling it an evil crime motivated by racial hatred.

Lawrence was stabbed to death in the unprovoked attack, lasting only around 10 seconds, by a gang of white youths. The trial had heard that at least three more people had been in the gang, all of whom are still at large.

The victim's parents had fought a long legal battle to bring their son's killers to justice, forcing Britons to face up to the casual racism that was still rife in an increasingly multicultural country.

A totally innocent 18-year-old youth on the threshold of a promising life was brutally cut down in the street in front of eye witnesses by a racist, thuggish gang, Treacy told a packed courtroom at the Old Bailey, London's central criminal court.

Dobson, now 36, and Norris, 35, were found guilty on Tuesday after a six-week trial that hinged on new scientific evidence presented by prosecutors.

The relatively light minimum sentences reflect the fact that Dobson and Norris were under 18 when Lawrence was murdered.

ECHOES OF ROSA PARKS

A lawyer who had previously represented the Lawrence family said the case was a watershed for British society and had echoes of the 1950s bus boycott that helped to transform race relations in the United States.

The Stephen Lawrence case was a Rosa Parks moment for British society, Matthew Ryder told BBC Radio 4.

The (subsequent) inquiry took us beyond the crude, violent sort of racism which every reasonable person would condemn and it led us towards the more subtle forms of racism and stereotyping which a lot of people previously dismissed.

The case became a catalyst for change after exposing deep-rooted failings in London's Metropolitan Police.

A 1999 report by senior judge William Macpherson said the murder had exposed institutional racism in the force and accused officers of incompetence and a failure of leadership.

The Lawrence case also helped end the 800-year-old judicial doctrine of double jeopardy, which had previously prevented suspects from being tried twice for the same crime.

Dobson was acquitted of the murder in 1996 when a private prosecution brought by the teenager's parents collapsed. The Court of Appeal quashed that acquittal in May 2011 and said Dobson could stand trial again, a decision made possible after double jeopardy was scrapped in 2005.

The bravery and dignity of the victim's parents, who were born in Jamaica and buried their son on the Caribbean island, struck a chord with families across Britain.

Nelson Mandela gave them his backing during a visit to Britain shortly after the killing in 1993.

Attention will now turn to trying to prosecute three or four other men in the gang that swallowed up and stabbed Lawrence in the brief but coordinated attack on a suburban London street.

The other people involved in the murder of Stephen Lawrence should not rest easily in their beds, London police commissioner Bernard Hogan-Howe told reporters shortly before sentencing. We are still investigating this case.

(Reporting by Keith Weir; Editing by Steve Addison)