The mother of murdered Emma Caldwell has made an emotional plea for information on the 12th anniversary of her daughter's death.

Margaret Caldwell spoke as police launched a new forensic search of the woodland site in Roberton near Biggar in South Lanarkshire, where her body was discovered in 2005.

Emma's clothing and the belongings from when she went missing have never been found and the new search aims to recover any of those items, which would bring clear forensic opportunities that could assist the inquiry.

Mrs Caldwell thanked the team of detectives that have been working on the case.

She said: "We have come here today on the anniversary of my daughter Emma's disappearance to thank and support the police for all their hard work and persistence in trying to find the person who took her life 12 years ago.

"Today is always a difficult day for my family, as we are usually at home thinking of Emma, each in our own way.

"Every day I think of Emma, every day I grieve for her, as a mother I know my pain will never end."

The grieving mother also urged people to come forward as she pledged to "never give up" fighting for justice for her daughter, who would have turned 39 in October.

She said:"I am here to make a direct appeal to those who know or suspect who the killer is. Please do the right thing, as long as the killer is still out there another life could be in danger.

"If you are the one who took Emma's life then I ask you to come forward - living with the guilt of taking her life must be dreadful.

"But if you have no conscience, then be aware my family and I will never give up on fighting for justice on Emma's behalf. We can do no less for we love and miss her every day, not just today."

Detective superintendent David McLaren, who is leading the investigation, has vowed to undertake a thorough examination of "facts, forensics and detailed searches of new areas of interest".

He said: "Finding the person or people responsible for Emma's murder is a priority for us. It is important that her mother, Margaret finds peace after all this time.

"We have been working tirelessly to find that vital piece of evidence that will allow us to put the person that killed Emma behind bars and I firmly believe that there are people out there who can assist.

"The area where Emma was found is crucial in this investigation. I'm particularly keen to hear from anyone who has been involved in prostitution and who may have been taken to the woods near Roberton."

He added: "It's a remote location and would take around 40 minutes to travel there from Glasgow city centre.

"Even if you can't be sure if it's the same location you were taken to, please get in touch if someone has taken you out with the city centre.

"I understand that some people are reluctant to come forward but we are not looking to cast judgments on people, I am only interested in finding information that could help us."

Detectives now believe Emma may have been seen at the bottom of Argyle Street in Glasgow on the night she went missing on Monday, April 4, 2005.

Previously, the last recorded sighting of Emma was on Butterbiggins Road in the south side of Glasgow.

Emma may have been seen getting into a black saloon-style vehicle, similar to a BMW, that may have originated from the Dumfries area.

Mr McLaren said: "We are determined to do everything possible to find Emma's killer; if you knew, or had an association with Emma or have any information that would assist, please contact us.

"My focus is not the activities you were involved in at the time, I just want to find out what you know and I'm asking you to get in touch with us.

"Perhaps there is something, which at the time, you never disclosed. However, 12 years have passed with no justice for Emma or her family."

He added: "Please, if you have any piece of information which you think could be of interest to us, get in touch.

"I'd like to finally appeal directly to those closest to Emma's killer and who have suspicions. You may be parent, a brother, a sister or partner of the person who took Emma from this world.

"I'd ask you to look in the mirror and ask yourself how you would feel if Emma was your daughter or sister. I need you to do the right thing and get in touch."

The Caldwell family solicitor, Aamer Anwar, said: "Today is a heartbreaking day for Emma's mother Margaret, she has lived through 12 terrible years of grief and sadness but still has a hope.

"If the killer is reading or watching he should know there will never be a time limit on justice for Emma Caldwell.

"This appeal today is not only for Emma, but also to the women who will have been hurt by this man or the friends or family who were too scared to speak out 12 years ago.

"If you know anything, saw anything or can help in any way then please have the courage to come forward and speak to the police in total confidence."

Anyone with any information is asked to contact Police Scotland on 101 or alternatively, please call Crimestoppers on 0800 555 111 where information can be given anonymously.