Police officers lead Manuel into court during his appeal
Vital information about Scotland's most notorious serial killer may have been suppressed to ensure he was hanged, a legal expert has claimed.
Peter Manuel was executed at Barlinnie prison in Glasgow in 1958 after being convicted of murdering seven people.
Dr Richard Goldberg, of Aberdeen University's law school, believes evidence about Manuel's mental health was withheld from the court.
He called on government archives on the case to be opened to the public.
Manuel, who was born in the US but moved to England with his family at the age of six, served jail terms for rape and sexual assault before moving to Glasgow in 1953.
In an orgy of violence between 1956 and 1958, he was responsible for killing at least seven times, although it is generally believed the true figure was closer to 15.
Background to the 1950s serial killings
While awaiting execution in prison, he is said to have admitted killing up to 18 people.
Manuel was convicted of the murder of three female members of the Watt family, including a 16-year-old girl, in a house in Burnside by shooting them in the head at close range.
He also butchered a family-of-three in Uddingston, Lanarkshire, as they slept, and 17-year-old Isabelle Cooke as she walked to a dance at Uddingston High School.
When detectives later took Manuel to the field where he buried Isabelle and asked where her body was, he replied: "I'm standing on her now."
The guns he used to murder his victims are still held in the Strathclyde Police museum.
There were few tears of sympathy for the mass murderer when Lord Cameron donned his black cap to pass the death sentence to make Manuel one of the last people to be executed in Scotland.
In my view insufficient weight was given to that evidence and also to the fact that Manuel suffered from temporal lobe epilepsy
Dr Richard Goldberg
But Dr Goldberg, whose father witnessed a medical examination of Manuel while working as a consultant at the Western Infirmary in Glasgow, said he believed Manuel may have escaped the gallows if the court had been told the full extent of his health problems, which included a form of epilepsy many believe can cause criminal behaviour.
He believes that the possibility of a mental disorder - which would have led to a diminished responsibility verdict rather than execution - was not adequately explored during the trial.
Dr Goldberg added: "I think there was considerable evidence that he was a psychopath, there was debate over whether there should be a reprieve, and in my view insufficient weight was given to that evidence and also to the fact that Manuel suffered from temporal lobe epilepsy.
"To me it is in the public interest that we have access to this information, that the public should see that justice was done properly, and they should have access to everything in the Manuel files.
"I think it is remarkable that 50 years after his trial there are still files that are closed and there is still uncertainty about what evidence still lies there."
He told BBC Scotland he had come up against a "brick wall" when trying to access some files.
He added: "When you read the files you see the pressure from the Scottish Home Department.
"They look at this issue of his psychopathic personality and they say 'We don't think he's a psychopath, but even if he is a psychopath he's a very marginal psychopath', so there is a pressure on people at the time to get him hanged.
"The problem is that psychopathic personality disorder still is not a basis for a plea of diminished responsibility, unlike in England, and this remains an anomaly."
Many of the papers used in Manuel's case were sealed for 75 years in 1958.
Journalist Russell Galbraith, who covered Manuel's trial, said there was little opposition to the decision to execute him at the time, even from anti-capital punishment protestors.
He said: "I don't remember any great enthusiasm from people trying to save Manuel, I must say, although there was obviously an abhorrence at the death penalty in many places."
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