The families of murdered Helen Scott and Christine Eadie hoped their 30-year wait for justice was finally coming to an end.
The bodies of the two 17-year-olds had been found six miles apart in East Lothian in October 1977.
One of Scotland's biggest-ever investigations eventually saw convicted murderer Angus Sinclair, 64, stand trial for the killings.
But the agony of the families continued after the trial collapsed in controversial circumstances in 2007.
The Scottish legal system's rules on double jeopardy made it impossible for prosecutors to again indict Sinclair for what had become known as the World's End murders, after the Edinburgh pub in which Ms Scott and Ms Eadie had last been seen.
Relatives of the two teenage girls were given fresh hope when Scottish Justice Secretary Kenny MacAskill asked the Law Commission to carry out a review of the double jeopardy rule, which prevents people standing trial twice for the same offence.
There is cross-party support in the Scottish Parliament for scrapping the rule, as happened in England and Wales in 2003.
However, the commission's long-awaited report, which it spent two years compiling, has recommended that any changes made to double jeopardy are not applied to cases retrospectively, even when compelling new evidence has come to light - as is said to be the case with the World's End murders.
Opposition politicians reacted angrily to the announcement, with the report being dismissed as a "disappointing fudge" by the Scottish Conservatives.
While stressing that the commission's views would be "carefully considered", Mr MacAskill signalled the Scottish government was preparing to introduce legislation which would make major changes to the existing rules on double jeopardy.
This would effectively put the issue in the hands of MSPs at Holyrood.
Morain Scott, the father of Helen Scott, said he was "deeply disappointed" by the commission's recommendations, and hoped parliament would come to the "right decision".
Sinclair, a convicted murder with a brutal history of sex offences and violence, was acquitted at the High Court in September 2007 after trial judge Lord Clarke ruled the Crown had insufficient evidence to proceed with the case.
Defence QC Edgar Prais successfully argued the prosecution had failed to provide evidence that the girls had been abducted from Edinburgh, or to show that any sexual encounter between Sinclair and the girls had not been consensual.
Although it was beyond question they were murdered, there was no evidence to link Sinclair - who was said to have acted along with his late brother-in-law Gordon Hamilton - to their deaths, Mr Prais told the trial.
Scotland's top prosecutor, Elish Angiolini QC, entered the ensuing row over the judge's ruling and the Crown's handling of the case when she told Holyrood she believed there had been sufficient evidence presented for the jury to be allowed to decide on Sinclair's guilt or innocence.
Her comments were criticised by Scotland's most senior judge, Lord Hamilton, who said the independence of the judiciary was under threat.
Ms Eadie and Ms Scott, who had met at Firrhill High School in Edinburgh, had been enjoying a night out with friends in Edinburgh on 15 October 1977.
They visited several pubs before arriving at the busy World's End, on the Royal Mile, at about 2200 BST.
Witnesses later said they remembered the girls talking to two men, one of whom had a "brooding presence".
When they left with the men about an hour later, one of the girls - thought to be Ms Scott - was said to have been drunk and fell over in the street.
She was helped to her feet by a policeman, who said she walked off down the street with a "shifty-eyed man" who had been standing nearby.
Ms Eadie's naked body was found the next day by dog walkers at Gosford Bay, Aberlady, in East Lothian. She had been bound and gagged with her tights and underwear, badly beaten, sexually assaulted, and strangled to death.
Her friend Ms Scott was found dead later on the same day in a field next to the Huntingdon to Coates road, close to Haddington.
She was also naked from the waist down, and had been sexually assaulted and badly beaten.
Clothing and other items which had been taken from the from the girls have never been found.
And more than 30 years later, the families of both Ms Scott and Ms Eadie are still waiting for justice to be done.