It was a crime that shocked the city of Glasgow.

A promising 20-year-old science student Alison Murray with a brilliant future found strangled in a beauty spot known as Bluebell Woods.

One of the city's biggest ever murder investigations would result in suspicion falling on a member of her own family.

It would also lead to a double murder conviction that was still being challenged more than 20 years later.

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Alison, of Southdean Road, Drumchapel was in her final year of a four-year honours microbiology and genetic engineering course at Strathclyde University and was due to sit her finals the following week.

On May 23, 1986, she had gone for a walk that Friday evening in nearby Bluebell Woods - also known as Garscadden Woods - to clear her mind before going back to her studies. But Alison never returned.

Around 10 pm she was attacked, sexually assaulted, strangled with her own bra, and left for dead.

Her body was found by children in some bramble bushes the next day and she was completely naked apart from a pair of socks though her hands were still in the sleeves of her anorak.

Her other clothing and coins from her jeans were found scattered nearby.

Unusually her gold watch had not been taken and her credit cards were found in her purse in a pocket.

So clearly theft had not been a motive but why had a popular young local woman been so brutally murdered and why?

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Mr and Mrs Murray 

Alison, 20, was one of seven children and lived at home with her mother Elizabeth and step-father Iain.

In an area of high deprivation, she could look forward to a career as a professional woman and a chance at a better life.

Police conducted house to house inquiries and hundreds of posters appealing for witnesses were distributed across the sprawling housing estate.

They believed that whoever had carried out the attack probably belonged to the local Drumchapel community.

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Though the Bluebell Woods was a popular beauty spot it was also used by local teenagers for drinking, sniffing glue, and illicit sex.

Her stepfather Iain Murray snr also made an emotional plea, declaring:''I feel no hatred for anyone who did this. I know Alison wouldn't have had any hatred. I want them caught because I know he is liable to do this again and the thought of it happening to any other wee lassie is too much to bear.''

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Three weeks into the investigation suspicion fell on her half-brother Iain Murray, 17, and his pal Brian Wilson, 18, who had already given statements to detectives and admitted being together on the day of the murder.

However, crucially there were discrepancies in their accounts.

They were both interviewed separately on June 15 at Drumchapel and Clydebank Police Offices where they they both admitted murdering Alison.

Crucially the two also revealed information about her death - called specialist knowledge - which could only have been known to the killers.

Both were charged with murder and on September 23 1986, their trial began at the High Court in Glasgow.

Crucially the police had no eye witnesses to the crime or forensic evidence.

All they had was two similar confessions by both youths made at the same time, at different police offices.

The basis of the prosecution case was that Alison chanced on her step-brother and Wilson while they were committing a sex act with each other in the woods.

Both teenagers were terrified that she would tell their parents and friends and they would be humiliated.

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Alison was subsequently chased, stripped and subjected to a sexual assault before her bra was knotted tightly round her neck.

A key piece of evidence was another confession Iain Murray had allegedly made to his dad Iain snr in Maryhill Police Office on June 17 which had been heard by a police officer Detective Constable Eddie Hutcheson.

In his charge to the jury, judge Lord Robertson said the alleged confessions were critical to the Crown case. Apart from that he described the evidence against the accused as "sparse."

However the jury found the two teenagers guilty of the murder on October 10 - which would have been Alison's 21st birthday.

Both youths were given life sentences and dubbed the Beasts of Bluebell Woods a name that has stuck with them ever since.

In 1997 in a macabre twist Alison's father, now 52, was found dead in a lane in Balloch, Dunbartonshire having taken his own life.

He had been due to appear at the High Court in Glasgow the next day on historical sex abuse charges against children.

Over the years Murray and Wilson continued to plead their innocence claiming they had been coerced by police into admitting their guilt. Murray also denied confessing the murder to his father at Marshall Police Office Both men lost an initial appeal in 1987 against their convictions.

However in 2004 their case was taken up by the Scottish Criminal Cases Review Commission, which investigates possible miscarriages of justice.

Five years later following a lengthy investigation the case was heard by three appeal judges in Edinburgh.

The men's claims that they were wrongly convicted was backed by Professor Gisli Gudjonsson, a former detective in Iceland and then one of the world's leading authorities on interrogations.

Murray's lawyers argued his confession evidence was unreliable because he was a vulnerable teenager under pressure.

Now freed from jail he was there in person for the hearing.

Wilson however had died earlier that year in Saughton Prison in Edinburgh.

He had been released in 2001 after serving 15 years of his life sentence.

The Glaswegian was then recalled after being convicted of breach of the peace offences in 2007 against two girls in his new home in Tranent, East Lothian.

However in June, 2009, both Murray and Wilson's appeals were thrown out.

Lord Wheatley said the disputed confessions were remarkably similar and included the sort of detail likely to be known only to the killers.

One of the officers involved in the original murder investigation was Detective Sgt Donald McKinnon, then a member of the elite Strathclyde Serious Crime Squad.

He retired from the police in 1996 after 31 years service at the rank of Detective Inspector.

His main role then was to do house to house inquiries in the Bluebell Woods area in a bid to trace witnesses to the attack.

He found himself involved in one of the key moments in the investigation when Murray admitted the crime to his father Ian snr in police waiting room.

Donald had been asked by his boss to go to Longriggend Prison near Airdrie with two other detectives where Murray was being held awaiting trial.

They were to take Iain Murray to Maryhill Police Station for an identity parade.

When Donald got there he was astonished to discover Iain Murray snr was also at the police station.

The retired cop said:"When we got there we were told by a senior officer that Murray's father was to be allowed to speak with his son before the parade.

"I said it shouldn't happen but I was over ruled.

"I told Eddie to go into the room not because we expected an admission but in case anything untoward happenned.

"One possibility was that the father could have attacked his son for killing his daughter.

"We also searched the father just to be on the safe side.

"Eddie came out and told me the son had admitted the murder in front of his father, the details of which he then wrote down."

Donald says their boss was initially reluctant to use the confession against Murray.

He added:"I said that's not your decision that is one for the Procurator Fiscal and the Lord Advocate.

"I think he realised that he shouldn't have let the father in to see his son in the first place.

"We gave the statement to the murder incident room manager, he put it in the system and the Crown decided to go with it."

DC Hutcheson later gave evidence about the alleged confession at the High Court.

Donald added:"We thought it strange allowing a guy who had been charged with murdering his sister to be allowed to speak to their father afterwards.

"The last thing in our minds was someone blurting out something like a confession.

"But I think that is what may have convicted him in the end."