Relatives of a woman brutally murdered more than 11 years ago have made a direct appeal to the killer to end the family's "nightmare" by turning themselves in to the authorities.

They vowed "there will never be a time limit on justice" for Emma Caldwell , and warned it is "inevitable" other women will have suffered at the killer's hands.

Ms Caldwell, 27, was found dead in woods near Biggar, South Lanarkshire, in May 2005.

She had previously turned to drugs, then prostitution to fund her habit, following the death of her sister.

The Crown Office asked Police Scotland to reinvestigate the unsolved case in 2015 after the original investigation failed to bring the killer to justice.

Ms Caldwell's mother Margaret Caldwell, uncle Jim Coyle and family solicitor Aamer Anwar met with Scotland's top prosecutor, Lord Advocate James Wolffe QC, on Thursday.

Speaking afterwards on the family's behalf, Mr Anwar said they wanted to talk directly to the killer.

He said: "Eleven years ago when you took Emma's life, you tore apart her family's lives forever. They were unable to bury Emma for some two years, her mother Margaret has never been able to grieve, and when William, Emma's father, died from cancer in 2011, he made his family promise they would never give up fighting for justice.

"Today, Emma's family has one simple request for the killer, end this nightmare by giving yourself up to the authorities.

"If you fail to do so, then you should know there will never be a time limit on justice for Emma Caldwell.

"Sadly it is inevitable that other women will have suffered at the hands of this killer and he will have aroused suspicions in his friends and family.

"The Caldwell family urges those who have such information to have courage and come forward and speak to the police in total confidence."

Four men were arrested over Ms Caldwell's death in 2007 but the case later collapsed.

Mr Anwar said her family had felt "betrayed" by the original investigation by the then Strathclyde Police, but now wish to express their confidence in the fresh probe by Police Scotland.

A dedicated team of 25 officers, including some of Scotland's most experienced detectives, is working full-time on the inquiry, the solicitor revealed.

"The Caldwell family have been frustrated at the length of time the new investigation has taken, but the Lord Advocate tried to reassure the family that this is a painstaking complex investigation begun from scratch," Mr Anwar said.

He said investigating officers have outlined the "enormous scale" of the inquiry to him, with thousands of documents to be re-examined and numerous lines of inquiries generated.

Police Scotland is believed to have sought out expertise throughout the UK and worldwide, and it has commissioned the Metropolitan Police to review its investigative strategy.

Detective Chief Superintendent Gareth Blair said Police Scotland remains "absolutely committed" to the case.

"The reinvestigation is focused on a number of areas including forensic opportunities which were not previously available and is pursuing lines of inquiry," he said.

"We have been in regular contact with Emma's family since the start of the reinvestigation and have met with them and their legal representatives.

"We also continue to work under the direction of the Crown Office and Procurator Fiscal Service."

A Crown Office spokesman said: "In May 2015, Crown counsel instructed a re-investigation of the murder of Emma Caldwell. That investigation is complex and ongoing.

"The Lord Advocate today had the opportunity to meet with Emma Caldwell's family and to discuss the case with them."