Prosecutors being criticised over the collapse of the World's End murder trial were also accused today of denying justice to four Glasgow families.

Serial sex killer Angus Sinclair, 62, was yesterday cleared of killing Helen Scott and Christine Eadie, both 17, in Edinburgh in 1977 after a judge ruled there was insufficient evidence against him.

Criticism over the Crown's handling of the case, which took 30 years to bring to court, has come from both victims' families and politicians who today called for a full inquiry.

There were also fresh accusations today by senior officers from Strathclyde Police who claim a tactical decision meant four Glasgow families were being denied full justice.

They had pushed for the Crown to charge Sinclair with the murders of Anna Kenny, Hilda McAuley and Agnes Cooney who died similar deaths to Helen and Christine in 1977.

They also believed Sinclair who was brought up in St George's Cross and later lived in Maryhill and Govanhill, could be the killer of Frances Barker, murdered earlier that year.

Strathclyde Police's view was based on the theory of an FBI profiler who said all six murders had been carried out by the same man.

But senior officers claim the Crown had already secured a conviction for the death of Ms Barker and took the decision to separate the World's End deaths for which there was stronger forensic evidence.

One Strathclyde office was reported today as saying: "What they feared was that they would have exposed the Francis Barker case as a miscarriage of justice.

"Following on from Shirley McKie and Lockerbie there was no appetite for another. I was convinced Sinclair would walk unless they included all the cases together."

Another senior officer who worked on the World's End case said: "There is no forensic evidence in the Glasgow cases so there is no way they could be prosecuted."

Concerns about the Crown's handling of the case against Sinclair worsened yesterday after prosecutor Alan Mackay failed to turn up in court to hear Lord Clarke dismissed the charges.

Mr Mackay is understood to have gone to England and is believed to have contacted his family.

Lord Clarke agreed with defence counsel Edgar Prais, QC that the Crown had failed to prove that the girls had been abducted, raped and robbed, prior to being murdered A Crown Office spokesman said the case was brought after lengthy investigation because "the Crown was of a view there was sufficient evidence on which to base a prosecution." There is no right of appeal against the acquittal by the judge. DNA mystery led to trial being halted

ANGUS SINCLAIR was cleared of the World's End murders because the judge at the High Court in Edinburgh ruled there was not enough evidence against him for the trial to continue.

So the mystery of who killed Christine Eadie and Helen Scott remains.

Police sources suggested before the trial that DNA found inside a knot on a ligature used on one of the bindings to tie them up was the "smoking gun" proof needed to convict Sinclair, a double killer and paedophile who is still serving two life sentences.

But the jury never heard the evidence the media had been tipped off to look out for. The reason why may never be officially revealed.

DNA expert Dr Jonathan Whitaker, from the world-renowned Forensic Science Services lab in Wetherby, Yorkshire, had just begun to answer questions from advocate depute Alan Mackay, prosecuting, when he was interrupted by a legal objection from Sinclair's defence team.

The nature of the objection from defence QC Edgar Prais was never completely explained.

Lord Clarke told the jury yesterday: "I have reached the conclusion there was insufficient evidence in law to entitle you to reach a verdict, therefore you are not required to reach a verdict."

Sinclair had not said a word during the trial - apart from conversations with his lawyers.