Detectives have made a dramatic new appeal for information on the brutal murder of a 13-year-old schoolgirl more than 40 years ago.

Tracy Main was found dead with multiple stab wounds in her tower block home in the Gorbals in Glasgow in February 1980.

READ MORE: Glasgow Crime Stories: The murder of Tracy Main

Glasgow Times:

A 43-year-old neighbour Thomas Docherty was charged with her murder but was found not guilty and walked free from the High Court in Glasgow after a legal blunder by the man leading the investigation.

Police Scotland say they are still treating the murder as a cold case four decades later and would like to hear from anyone with fresh information.

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Glasgow Times:

Detective Chief Superintendent Laura Thomson, who oversees Homicide and Governance Review, said: "We understand how devastating it is for loved ones to not have the type of closure a conviction can help to bring.

"The death of Tracy Main is considered an unresolved murder and these cases are never closed by Police Scotland.

"Should any new information be received detectives in our Homicide and Governance Review team will thoroughly assess this and investigate further, wherever necessary.

"Anyone who may have information about Tracy's death is urged to contact Police Scotland via 101 or contact the independent charity Crimestoppers anonymously on 0800 555 111."

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Glasgow Times:

It's understood that there has been no recent review or re-investigation of Tracy's death.

However, developments in forensic science often provide detectives with the necessary breakthrough.

New inquiries will also be carried out if members of the public come forward with fresh evidence.

Tracy Main's body was found by her mother after she came home from work.

She was slumped against the settee of the lounge, her trousers at her knees and seven stab wounds to her chest.

A post mortem also showed that a hand had been placed over Tracy's mouth to stop her screaming.

The attack had happened at her home in Norfolk Court on February 5 while she was off sick from school and her parents were both at work.

Though her clothing had been removed there was no evidence of a sexual assault.

Suspicion fell on Thomas Docherty who had the mental age of an eight-year-old and had only moved into his flat six weeks earlier.

On the eve of his trial in June 1980, Docherty's solicitor Joe Beltrami, and QC Hugh Morton discovered a major flaw in the prosecution case.

Docherty had been charged by Detective Chief Inspector Les Brown who had led the murder hunt.

When both men checked the DCI's statement they discovered he hadn't warned Docherty of his right to remain silent while cautioning him.

When this was raised during the trial the judge Lord Cowie brought proceedings to a halt and cleared the court.

After being given more details of DCI Brown's error the jury were called back in and instructed by Lord Cowie to find Docherty not guilty.

An angry mob had quickly gathered outside the building when they learned of the outcome.

Docherty had to be smuggled out of court and spent two nights in a police station for his own protection.

A full investigation was launched by both Strathclyde Police and the Crown Office into the blunder and why it had not been spotted earlier. The controversy was even raised in the House of Commons by the local MP A place was found for Docherty in a social work hostel at a secret location in England where he remained never returning to Glasgow.

In his 2005 memoir, 'Glasgow Crimefighter' DCI Brown admitted that he had made a "bad" mistake over his failure to administer the correct caution.