Three men, who they believed to be the killers of their son Stephen, walked out of the dock at the Old Bailey, unpunished and now unpunishable. Doreen Lawrence collapsed in tears. Neville Lawrence froze, unable to believe his eyes.
The couple had pinned their hopes on the trial at the Old Bailey in April 1996. Two years earlier, with the backing of their legal team, solicitor Imran Khan and eminent QC Michael Mansfield, they launched a private prosecution of the men widely regarded as the prime murder suspects.
It was the only route that remained open, they believed, after the Crown Prosecution Service discontinued its case.
Not everyone agreed. Howard Youngerwood, the senior CPS lawyer who took the decision to drop the charges, was horrified.
He told Mr Khan that he was bound to fail because of the unreliability of the identification evidence of Duwayne Brooks, Stephen's friend, and begged him not to proceed.
It would have been far better, said Mr Youngerwood, to wait for new evidence to emerge so that the CPS prosecution could be reactivated. He told the public inquiry that when he discovered that the Lawrences planned to ignore his advice, "I was so desperate, I collapsed in the street".
Others observers questioned whether Mr Mansfield and Mr Khan - celebrated criminal defence lawyers, but with no experience of conducting a prosecution - had the necessary expertise to handle the case.
But the Metropolitan Police, who had reopened the murder investigation under an energetic detective superintendent, Bill Mellish, was happy to co-operate.
They gave the family a surveillance video that showed the suspects brandishing knives and fantasising about killing black people.
The Lawrences - who raised pounds 45,000 to finance the prosecution - received a further morale boost when Ian Johnston, the Metropolitan Police's Assistant Commissioner, attended the committal proceedings at Belmarsh Magistrates Court as a public display of support.
At Belmarsh, charges against two of the suspects - Jamie Acourt and David Norris, both 18, were dropped because of insufficient evidence. But Dobson, 18, Neil Acourt, 20, and Luke Knight, 18 - were sent for trial.
The case hinged on Mr Brooks, who had picked out the three defendants at identification parades. In legal argument, though, doubts were cast on his evidence, and the trial judge, Mr Justice Curtis, said Mr Brooks did not know whether he was "on his head or his heels".
With his evidence ruled inadmissible, Mr Mansfield had no option but to abandon the case, and the three were formally acquitted on the direction of the judge, who praised the Lawrences' "statesmanlike" conduct.
The video - which showed Neil Acourt waving a knife said to be similar to the one used to kill Stephen - was never shown to the jury. The private prosecution was a desperate measure by a family who had been let down by police and the prosecuting authorities.
But tragically, since it is a principle of English law that people cannot be tried twice for the same offence, its effect was to place the three men beyond the reach of justice. The case against the other two was so seriously undermined that the Lawrences will now probably never be granted their dearest wish: to see their son's murderers behind bars.
The QC: Michael Mansfield
Michael Mansfield, a vegetarian who enjoys cycling, takes to the upstairs room of his London home whenever he feels frustrated to bang a battered old drum kit.
One of the country's best-known lawyers, his clients have included the Angry Brigade, the Birmingham Six, the Bridgewater Three, Arthur Scargill and Patrick Nicholls, who served 23 years for a murder that never happened.
The son of Conservative-voting parents, his interest in the law started when his mother defended herself when she was wrongly fined pounds 10 for illegal parking.
After studying philosophy and history at Keele University, Mansfield, 57, taught at a polytechnic and studied for his Bar exams by a correspondence course. He failed land law three times before passing and became a QC in 1989.
The Solicitor: Imran Khan
Imran Khan not a solicitor new to controversy. After representing two Asian men accused of murdering the white schoolboy Richard Everitt, he received death threats.
He was also told by police he should not attend a demonstration in north London being held for the men, who had been convicted of murder and violent disorder.
"I can appreciate that people might be angry and frustrated, particularly those who have lost someone, but making threats to my life goes beyond reasonable behaviour," he said. He was at the demonstration.
Slim and charming, he often represents high-profile race-related cases.
Within days of Stephen Lawrence's murder, he was representing his parents, Doreen and Neville. With Michael Mansfield, he has worked beside them since.