How cigarette butt helped solve 30-year murder mystery
2025-01-17
Category: news

A cigarette stub recovered from Mary McLaughlin's flat provided the first clue to her killer's identity - more than 30 years after she was strangled.A matching DNA profile was later discovered hidden in the knot of the dressing gown cord used to murder the mother-of-eleven.The breakthrough initially baffled cold case detectives as the prime suspect was a prisoner in Edinburgh when Mary, 58, was found dead in the west end of Glasgow.But a governor's log book confirmed serial sex offender Graham McGill was on parole when the grandmother was killed.And it revealed he returned to his cell within hours of leaving Mary's home in the early hours of 27 September 1984.
A new BBC documentary, Murder Case: The Hunt for Mary McLaughlin's Killer, tells the story of the cold case investigation - as well as the devastating impact the murder had on Mary's family.Senior forensic scientist Joanne Cochrane said: "There are some murders that stay with you. "Mary's murder is one of the more disturbing cold cases that I've dealt with."Mary spent her last night out drinking and playing dominos in the Hyndland Pub, now the Duck Club, which looks onto Mansfield Park.She left the bar, on Hyndland Street, alone between 22:15 and 22:30 to walk less than a mile home to her flat.Along the way she called into Armando's chip shop on Dumbarton Road, where she joked with staff as she bought fritters and cigarettes.A taxi driver, who knew her as Wee May, later told how he saw a lone man following her as she walked bare foot along the road carrying her shoes. 
The sequence of events which led to McGill ending up in Mary's third-floor flat in Crathie Court is unknown but there was no sign of forced entry.Once inside, he launched a savage attack on a woman who was more than double his age.In an era before mobile phones, Mary was not in frequent contact with her large family who lived in Glasgow, Lanarkshire and Ayrshire.Once a week, one of her sons, Martin Cullen, would call in to see her.But when the then 24-year-old turned up at the flat on 2 October 1984, there was no answer and a "horrible smell" when he opened the letterbox.Mary was found dead inside, lying on her back on a bare mattress.Her false teeth were on the floor and a new green dress she had worn to the pub had been put on her back-to-front.
Former senior investigating officer Iain Wishart described the crime scene as "particularly cruel".He added: "The tragic thing is that she would have been looking into his eyes when he committed the murder."A post-mortem examination concluded that Mary had died after being strangled at least five days earlier.Detectives gathered more than 1,000 statements in the months that followed but the hunt for Mary's killer resulted in a series of dead ends.The following year the family were told the investigation had been closed but one CID officer urged Mary's daughter, Gina McGavin: "Don't give up hope."
Mary had 11 children by two fathers and was well known in the local community.But daughter Gina told the documentary there were tensions as she left her first six children and the five she had with a second partner.She said: "I thought that there was a hidden killer within the family."Gina, who wrote a book about her mother's murder, said she shared her suspicions with the police.She added: "My siblings were of the same thinking as me in 1984."It was one of her own children that had been involved or knew something more but we couldn't prove anything."
By 2008, four separate reviews had failed to yield a profile of the suspect.The fifth review was launched in 2014 and the eventual breakthrough was made possible by a new DNA-profiling facility at the Scottish Crime Campus (SCC) in Gartcosh, North Lanarkshire.Previously experts could look at 11 individual DNA markers but the latest technology was capable of identifying 24.This dramatically increased the odds of scientists obtaining a result from smaller or lower-quality samples.Tom Nelson, director of forensics for the Scottish Police Authority, said in 2015 that the technology would make it possible to "reach back in time, with the potential to rekindle justice for those who had all but given up hope".
The samples gathered in 1984 included locks of Mary's hair, nail scrapings and cigarette ends.Ms Cochrane, who is based at the SCC, was asked to review evidence from the scene that had been preserved in paper bags for 30 years.She said: "They didn't know about DNA profiling at that time."They didn't know the potential held in these items."They couldn't possibly have known the value that it might have had."The senior forensic scientist said the original inquiry team showed "amazing foresight" to preserve evidence.
The breakthrough eventually came from an Embassy cigarette end stubbed out on an ashtray on the living room coffee table.It was of particular interest to the cold case team as Mary's preferred brand was Woodbine.Ms Cochrane said she hoped technological advances would enable her to obtain trace levels of DNA.She told the documentary: "Then we get this Eureka moment, our Eureka moment, where the cigarette end, which previously didn't give us a DNA profile is now giving us a full male profile."This is something we have never had before and it is the first evidentially significant piece of forensic science in the case."It was sent to the Scottish DNA database and compared against thousands of profiles of convicted criminals.The result was delivered to Ms Cochrane in a form, via email.She quickly scrolled to the bottom and saw a cross next to the box: "Direct Match".The expert said: "It was a real goose bumps moment."It identifies a person called Graham McGill and I can see on the form that comes back to me that he has got serious convictions for sexual offences."After more than 30 years we had an individual that matched that DNA profile."
But the long-awaited development created a conundrum when it emerged McGill - who had convictions for rape and attempted rape - was a prisoner when Mary was murdered.Records also showed he was not released until 5 October 1984 - nine days after the grandmother was last seen alive.Former Det Sgt Kenny McCubbin was tasked with solving a mystery that did not make sense.Ms Cochrane was also told more forensic evidence was needed to build a compelling case.That quest led her to another "time capsule of DNA" - the dressing gown cord used to strangle Mary.Ms Cochrane believed there was a fair chance the person who tightened the knot may have touched the material now concealed within it.Under the glare of fluorescent lights in her lab she slowly untied it, piece by piece, to expose the fabric for the first time in more than three decades.She said: "We found that key piece of evidence - DNA matching Graham McGill - on the knots within the ligature."He had tied that ligature around Mary's neck and had tied those knots to strangle Mary."
Separately, traces of McGill's semen were also found on the grandmother's green dress.But Mr McCubbin, who has now retired, told the documentary the forensic evidence alone was not enough to secure a conviction.He said: "It didn't matter what DNA we had. "He's got the perfect alibi. How could he commit the murder if he was in prison?"Records were hard to find as HMP Edinburgh had been rebuilt at the time of the murder and, in an era before computers, paperwork had been lost.Mr McCubbin's quest eventually took him to the National Records of Scotland, in the heart of Edinburgh, where he tracked down the governor's journals.And a single entry changed everything.Next to a prison number was the name "G McGill" and the acronym "TFF".The former detective sergeant said: "That was Training For Freedom, which meant weekend home leave."The inquiry team discovered McGill was on two days weekend leave, with three days pre-parole leave added on, and returned to the prison on 27 September 1984.Former senior investigating officer Mark Henderson said: "That was the golden nugget we were looking for."
McGill was finally arrested on 4 December 2019 .At the time, he was still being managed as a sex offender, but was working in the Glasgow area as a fabricator for a company based in Linwood, Renfrewshire.Gina said the news came as a relief and added: "I never thought I would see it in my lifetime."McGill finally was found guilty after a four-day trial in April 2021 and jailed for a minimum of 14 years.The judge, Lord Burns, told the High Court in Glasgow that McGill was 22 when he strangled Mary but stood in the dock as a 59-year-old.He added: "Her family has had to wait all that time in order to discover who was responsible for that act knowing that whoever did it was probably at large in the community. "They had never given up the hope that some day they would find out what had happened to her."