THE father of murdered student Amanda Duffy has backed new double jeopardy laws that he believes will help families who have been let down by the justice system in the past.

Joe Duffy spoke after the Crown Office made a landmark legal move to pave the way for a second prosecution of Angus Sinclair, who was acquitted of the notorious World's End murders of Helen Scott and Christine Eadie committed 35 years ago.

Mr Duffy said it was "fitting" the Edinburgh case was the first to progress under the new double jeopardy legislation, as Sinclair's acquittal had led to the legal reform in Scotland that does away with the ancient legal principle that an accused cannot be tried for the same crime twice.

The murder of his own daughter, a promising drama student, 20 years ago, is one of a handful of cases being re-examined by police and prosecutors in light of the new laws.

Francis Auld stood trial for the murder of Ms Duffy, who was found battered to death on wasteground in Hamilton, South Lanarkshire, but the jury returned a not-proven verdict.

Mr Duffy said: "It is fitting the one to go though first is Angus Sinclair, as it is very much the case that sparked the whole thing into life.

"Probably the most abused word in the English language is closure. Following a murder you never get closure. To be honest it is bad enough somebody's life has been taken in this way but to have no justice, for the family to see a person walk free, often on a technicality, it's as if they have been offended against twice – first the loss of a loved one and then the justice system letting them down.

"It gives me hope that justice will be realised, not just for us but for the other families."

In 1995 Ms Duffy's parents won a civil action against Mr Auld and were awarded £50,000. Now 40, he lives in Sussex but has been re-interviewed by police in recent months.

Mr Duffy, who along with his wife Kate set up the support group Petal for those affected by murder and suicide following their daughter's death, added: "My hope is that double jeopardy is implemented properly. If you look at it from the perpetrators' point of view, they have the appeal process to go through.

"I know of one crime that was committed seven years ago and there have been 34 appeal hearings. It's absolutely ridiculous in terms of the cost and time."

At the time of her death, Ms Duffy was an aspiring actress and student at Motherwell College. She had been called to audition at the then Royal Scottish Academy of Music and Drama and was returning from a night out celebrating with friends when she was attacked.

She had been so badly beaten pathologists were unable to determine whether she had been injured by a weapon or with bare fists. She had had twigs thrust into her mouth and nose during the attack.

The Double Jeopardy (Scotland) Act 2011 set out five new conditions where an accused could be retried for a crime of which they were previously acquitted, including instances where "compelling new evidence" emerges.

A second prosecution can also be launched if evidence later emerges that an acquitted person has admitted to committing the offence, or where the original acquittal was "tainted" possibly by witness or juror intimidation.

Police are also re-investigating the murder of Indian waiter Surjit Chhokar in Overtown, Lanarkshire, in 1998.

A prosecution for the crime ended with the acquittal of three accused: Ronnie Coulter, Andrew Coulter and David Montgomery.

It is fitting the one to go though first is Angus Sinclair, as it is very much the case that sparked the whole thing into life