01/04/2012 07:58 EST | Updated 03/05/2012 05:12 EST

2 men in 1993 U.K. race murder get prison terms

Two men convicted this week by a British court in the killing of Stephen Lawrence were sentenced Wednesday to minimum prison terms, nearly two decades after the black teenager was stabbed in what has been regarded as a racially motivated attack.

Gary Dobson, 36, will serve 15 years and two months in prison, and David Norris, 35, received a term of 14 years and three months for the 1993 stabbing death in southeast London. The men were 17 and 16, respectively, at the time of the killing. Both have maintained their innocence throughout the case.

Justice Colman Treacy, however, on Wednesday called the crime a "murder that scarred the nation," the BBC reported.

"I'm sure that you knew one of your group was armed with a knife that night," he told Dobson and Norris, calling the incident "a brief but co-ordinated attack, a racist taunt, a charge and a swallowing up of Stephen Lawrence."

The sentences are considered life terms for juveniles in Britain.

Had they committed the crime in the last year, Dobson and Norris would have faced minimum terms of 25 years for a racially aggravated knife murder, the same as an adult sentence.

However, the judge was forced "by law to treat the pair as juveniles because their ages at the time of the crime were 17 and 16," CBC's Ann MacMillan reported from London.

The judge had some discretion to set a longer sentence, given the attack was racially motivated and that one of the gang involved in the killing carried a knife.

The investigation involved multiple court appearances by suspects over the years, but no convictions until Tuesday. It has led to strong criticism of London's Metropolitan Police, and a later investigation found the force was "institutionally racist" and had bungled evidence-gathering.

"The case is still seen as a key to changing attitudes to racial crime in Britain," said MacMillan. "It's also led to crucial change in the law."

Britain's double jeopardy rules now permit a second prosecution if compelling new evidence emerges.

Stabbed by youth gang

Dobson's father shouted out "Shame on you" from the public gallery after the sentence was announced at London's Central Criminal Court. Norris gave a thumbs-up sign to his supporters in the public gallery as he was led from court.

Outside court, Lawrence's mother, Doreen Lawrence, said the "the judge's hands were tied," so he couldn't hand out longer sentences.

She said the prison terms they were given, however, were "the beginning of starting a new life because we've been in limbo for so long."

Lawrence, 18, was stabbed by a gang of white men the night of April 22, 1993, as he waited for a bus in Eltham.

His friend, Duwayne Brooks, said one of the attackers called out racist insults as he approached.

Norris, Dobson and others were identified as suspects by police days after the murder, but faulty handling of evidence meant prosecutors were unable to convict them until now.

Two men, Neil Acourt and Luke Knight, were charged with Lawrence's murder in June 1993, but were never prosecuted until this week.

This year, the jury at the Lawrence trial was not told that Dobson already was in jail for a drug conviction. Norris had been in and out of prison for other convictions. In 2002, he was jailed after shouting a racist insult at a police officer and later jailed again for stealing a car.

Defence lawyer Stephen Moses said Dobson had no previous conviction for violence at the time of the attack and came from a loving family. Fellow defence attorney Stephen Batten said Norris's marriage had dissolved under the strain of the long investigation.