The death of Dorothy Niven is one of the most baffling ever investigated by police in Glasgow.

It led to a man being convicted of her murder then freed on appeal five years later – with the victim’s family later being refused an inquiry into her death after a lengthy court battle.

At the time of her death in June 1995, Dorothy, then 33, had split from boyfriend Richard Karling and was seeing a new man.

However, Karling had asked to see her so they met at the former Pancake Place in Union Street one afternoon.

During their meal she complained of feeling unwell and was suddenly sick.

Karling took her home by taxi to her place in the village of Busby on the outskirts of Glasgow and left her there.

The following day around 4.30pm he called an ambulance claiming he had just found her lying unconscious and face-down on her bed.

However, Dorothy had been dead for more than 12 hours.

The ambulance paramedic had also found her partially clothed.

A police surgeon called to Dorothy's house treated the incident as a “sudden death''.

Dr Ali-Alousi, who conducted a post-mortem examination also found nothing suspicious about her death.

However, local prosecutor David Green who was present at the post-mortem in Glasgow's city mortuary was not as satisfied.

He ordered a second post-mortem examination which was carried out two weeks later by pathologist Dr Marie Cassidy and a colleague from the University of Glasgow.

Dr Cassidy had also noticed that the dead woman's pants were on back-to-front and inside-out.

She concluded that Dorothy had been suffocated.

As a result, Mr Green then ordered police to treat the death as one of murder.

The main suspect was Karling who had taken her home after she fell ill.

There was no sign of a break-in to the dead woman's home and had probably known her killer.

Karling was charged with murder and stood trial at the High Court in Glasgow in December that year, 1995.

The jury were told that when Dorothy met Karling at the Pancake Place she was walking normally and seemed in good health. 

However, within a space of 10-15 minutes she became very unwell. 

She was heard to remark that she was embarrassed because people would think that she was drunk. 

Witnesses said Dorothy was as "floppy as a rag doll" when Karling helped her out of the diner into the taxi. 

By way of explanation, he told the taxi driver that she was in a diabetic coma.  

Dorothy was not seen again by anyone, apart from Karling, until about 4.30pm the following day after he made the 999 call for an ambulance to come to her house. 

It was the paramedics who then decided that the police should be called.

Karling was accused of spiking Dorothy's orange juice drink with the sedative temazepam in the Pancake Place.

When she was no longer able to resist and had passed out, it was alleged she had been smothered with a pillow. 

However, Karling blamed a new boyfriend for the alleged murder and claimed Dorothy was alive when he left her. 

Dr Cassidy also told a jury that she thought the pants had been put on after her death.

The victim's mother, Ivy Niven, from Mount Vernon, claimed Karling had once thrown her daughter into a bath of cold water in his house in Ayr.

It was also claimed he had told her: “If I can't have you no one else will.''

When they first started going out together, Karling was the general manager of a large television retail firm in Ayrshire.

They had meals in good hotels, enjoyed foreign holidays, and Karling claimed he gave her a car and furnished her flat.

But following a break she had to get a court order to stop him phoning or following her.

However, Dorothy agreed to see him again at their meeting in Union Street.

But by this time Karling had lost his well-paid job and he was living in a rented flat on housing benefit.

Advocate depute Mr William Totten, prosecuting, told Karling as he sat in the dock: “Dorothy was a young, attractive and vivacious girl and you were obsessed by her.

“You gave her a good time, and you had money to spend on her.

“The money, gifts and good times had run out and Dorothy had enough of the relationship.

“You would have been left without her, with nothing, and you decided to kill her.''

Karling also took to the witness box to give evidence in his own behalf.

Asked by defence lawyer Hugh Matthews why he had shown little emotion in the witness box, Karling replied: “My tears are inside me.'' 

Karling, who was from Ayr, was convicted of murder by a majority verdict.

The key evidence had been a Glasgow University drug test that found the sedative temazepam in Dorothy’s blood.  

However, Karling protested his innocence, particularly over the temazepam evidence, claiming he had been the victim of a miscarriage of justice.

His defence team commissioned reports from forensic pathologists which concluded that there was no scientific basis for saying that Dorothy had been suffocated. 

In March 1999, the Court of Criminal Appeal appointed Lord Kirkwood to hear the new forensic evidence.

There was a dramatic development the following September which blew the murder conviction wide open.

It emerged that blood-test results - which could have cleared Karling - had not been disclosed to the defence at the time of the trial.

They had since learned of a blood test carried out at Guy’s Hospital in London which revealed there had not been any temazepam present in Dorothy's blood stream at the time of her death.

They also had reports from their own pathologists who said there was no reason to believe Dorothy had been smothered.

Professor Sir Bernard Knight, of Cardiff University, said that the cause of Dorothy’s death should have remained "unascertained".

He claimed there was no evidence for suffocation.

Karling had been found guilty on the grounds of a University of Glasgow test that showed a small amount of the drug in Dorothy's blood. 

But the earlier test at Guy's Hospital in London showed no traces of temazepam and had not been disclosed to the prosecution.

At this point the Crown Office agreed there had been a miscarriage of justice and said they would not contest the appeal.

As a result of the new evidence the conviction was quashed.

After he left the court Karling, now 48, who had spent five years in jail, said: ''I'm still on cloud nine. It's total euphoria.''

In 2005 he obtained £892,000 in compensation for his five years behind bars after raising a civil action against the Scottish Government.

At the time he said: "I am really happy the executive did the right thing. They gave me a really good settlement. That reflects the level of the miscarriage of justice that had taken place."

Karling had been freed in June 2000, pending the outcome of the appeal, and in May the following year his conviction was quashed.

He told reporters said that "a fair chunk" of his compensation had disappeared in legal and other costs.

Dorothy's family have since sought an explanation into her death and maintain that the direct causes are unclear.

The Crown Office stated that a fatal accident inquiry or public inquiry would not be held.

In 2009, mum Ms Niven challenged the decision in a judicial review at the Court of Session in Edinburgh, arguing the failure to hold an inquiry breached European human rights legislation.

But in his ruling judge, Lord Malcolm stated: "There is nothing in the present case to suggest there are gaps or deficiencies in the investigations to date such as would undermine the protections and prohibitions contained in the domestic law, nor question the state's willingness to investigate and prosecute in appropriate cases."

His lordship added: "The fact that there remain unanswered questions does not cast doubt on nor undermine the ability of the criminal justice system in Scotland to operate in a manner which is capable of identifying criminal liability."

Speaking at the time, Ms Niven said she was disappointed but determined to continue her fight.

She added: "It is now 14 long and painful years since Dorothy died, and ever since that terrible night my son Paul and I have been living through a nightmare which will now drag on for even longer.

"But neither of us will rest until we find out the truth about how Dorothy died."