DR Marie Cassidy spent four decades telling the stories of the dead. She gave a voice to those who could no longer speak, victims of stabbings, gunshot wounds and blunt trauma, sifting through the debris of house fires or examining remains from freshly exhumed mass graves.

Cassidy, 65, began her career as a consultant forensic pathologist in Glasgow during the mid-1980s, a time when far too many of those who ended up on a mortuary slab did so as a result of the gangland warfare that raged in parts of the city.

She later worked in Dublin, first as Ireland's deputy state pathologist, then later becoming the first woman to hold the role as state pathologist, finding herself thrust into the public eye ("In Ireland, the obsession with death is unbelievable," she says).

It is two years since Cassidy – in her words – hung up her scalpel for the last time and a newly published memoir, Beyond The Tape, gives fascinating insight into her former world.

This same unflinching candour is present throughout our interview as we sit down (Cassidy at her home near London, me in Scotland) to reflect on her remarkable career. Here, she shares stories – and busts some myths – about life on the frontline of death.

A path to pathology

The middle of three children, Cassidy grew up in the village of Craigneuk and then Wishaw in Lanarkshire. Her late father was a coalman, and from the age of six or seven, she and her younger sister would help him with collecting the "tick money", owed by customers.

Cassidy decided to become a doctor after seeing her father spend long periods in hospital due to hardened arteries and several heart attacks. She was 15 when he died from a stroke. A few weeks later, Cassidy gained the grades in her Highers to study medicine at Glasgow University.

Meanwhile, her mother became the breadwinner. "When my dad became ill and then died, she had to take over the coal business and go out on the lorry," says Cassidy. "Not that she was carrying the bags of coal. She would have drawn the line at that.

"From being the housewife who sat and painted her nails until we came home from school, she suddenly had to become the man of the family. Our lives were always a wee bit different, but, as far as we were concerned, they were pretty normal and happy."

Finding her true vocation

Cassidy dissected her first body in an anatomy class during her second year at university. As her studies progressed, she had an inkling that working with the dead, rather than the living, may be where her strengths lay.

She recounts an internship spent stitching glass-ravaged faces, packing bleeding noses, putting plaster casts on fractured limbs, syringing ears and picking foreign bodies out of eyes. A stint working in A&E was the final persuasion she needed: Cassidy began her pathology training in 1979.

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"If it doesn't kill you, I don't know anything about it," she says, when we speak. "People will come up to me and say: 'I have this pain going down the back of my leg …' and I'll reply: 'Your leg is still attached to you, you are walking and talking, you are not dead.'"

Death, murder and No Mean City

Cassidy started out as a forensic pathologist in 1985. She remembers her tutor's shock when she told him that was her plan, rather than pursuing the highly regarded field of histopathology to diagnose and study disease in tissues and organs.

"He was stunned," she recalls. "In the mid-1980s forensic pathology had a poor reputation, to put it mildly: forensic pathologists were regarded as failed histopathologists, dealing with the deaths of the dregs of society."

Even so, the professor put in a few calls on her behalf. At that time, there were three forensic pathologists in Glasgow. They worked separately from the hospitals at the city mortuary on the Saltmarket. It turned out there was a job going and Cassidy was offered it.

HeraldScotland: Forensic pathologist Dr Marie Cassidy. Picture: Paul StuartForensic pathologist Dr Marie Cassidy. Picture: Paul Stuart

She would spend the next 13 years investigating unnatural deaths and homicides, from gangland shootings and stabbings, to drug deaths, road traffic accidents and suicides, carrying out more than 5,000 post-mortems.

Cassidy dealt with her share of murder victims – mainly stabbings. Weapons ranged from a seemingly innocuous pencil to ornamental samurai swords (the latter, she says, were "a common feature on living room walls in 1980s Glasgow").

Another often-seen cause of death was blunt trauma, principally head injuries due to punching, kicking or being struck with a weighty object, such as a hammer, a wheel brace or a rock ("People use the weapons that are available to them at that time").

A few years later guns entered the fray. "Up until then, Glasgow had a reputation as 'Stab City' and it was mainly knife crime we were dealing with," she says. "There was a change in the gangland killings. All of a sudden, we had this spate of shootings."

Cassidy visited the forensic department in Belfast to learn more about gunshot wounds, drawing on knowledge gleaned by her peers during the Troubles in Northern Ireland.

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"I was about eight months pregnant at the time and that caused a big stooshie because all of a sudden there was this strange woman appearing at scenes with their state pathologist. That was at the time of the Troubles, so shootings were 10 a penny."

Working in a warzone

Cassidy travelled to Bosnia in 1996 to assist the UN War Crimes Tribunal – her first of several trips – where she joined an international team of forensic pathologists investigating mass graves discovered following the conflict in the former Yugoslavia.

In 2000, she went to Sierra Leone to help recover the bodies of UN peacekeeping soldiers who had been killed in the civil war there. As the frontline fighting was briefly pushed back, a small team that included Cassidy rushed to excavate the remains from a trench.

It was a high-pressure situation and markedly different to their ideal working scenario. "It is like everything; you have got to cut your cloth accordingly," says Cassidy. "We made the decision that we had to get in and get these bodies. We only had a very short window of opportunity.

"The main thing was identification and to make sure the bodies were returned to their families. It wasn't like a murder elsewhere where you are conscious of not losing forensic evidence. The main concern was to get these bodies out as intact as we possibly could so we could identify them."

The same rang true of her work in Scotland where the loved ones of the deceased person on her table were never far from her thoughts. To that end, a Death Clinic was set up in Glasgow to allow grieving families to meet with a pathologist.

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"Someone has to come and identify the body," she says. "You are immediately faced with the reality of that death and who it is going to impact. It was always in my mind that the families should get access to all the information we could give them about a death.

"Often that is the only way people can move on. Some people never move on and some people get stuck. I would feel sad when I went to the courts and saw families that had become fractured because they were all dealing with grief in different ways.

"Someone will think: 'Pull yourself together, it happened six years ago.' If only it was so simple. We would all be rolling up our sleeves and getting on with the world. But it's not and everyone has to deal with things in their own way. That is life and how people deal with death."

Cold cases and hindsight

Among the high-profile cases Cassidy worked on in Scotland was the exhumation of John Irvine McInnes in 1996. He had been an early suspect in the Bible John murders in Glasgow.

Between 1968 and 1969, three women were found dead, having been beaten, strangled and sexually assaulted, after visiting the Barrowland Ballroom in the city's east end. Despite one of the most extensive manhunts in Scottish criminal history, their killer has never been found.

In 1993, the death of one of the victims, Helen Puttock, was reviewed by the police. A semen stain had been identified on her clothing in 1969 at the time of the original investigation and by the mid-1990s technology enabled a DNA profile to be obtained.

A decision was made to exhume McInnes's body and take samples for DNA analysis. As forensic pathologist acting for the Crown Office in this instance, Cassidy was at the grave in Stonehouse, Lanarkshire, as the exhumation took place.

HeraldScotland: Police officers at Stonehouse Cemetery, Lanarkshire, take the exhumed remains of John Irvine McInnes for DNA tests in Glasgow. Picture: Maurice McDonaldPolice officers at Stonehouse Cemetery, Lanarkshire, take the exhumed remains of John Irvine McInnes for DNA tests in Glasgow. Picture: Maurice McDonald

At the mortuary, bone samples were taken from the remains. "The best source of material for DNA analyses given the time frame," she writes in Beyond The Tape. "Unfortunately, despite our best efforts, the laboratory could not get a full profile and the results were described as inconclusive."

Cassidy believes that had they held off for another 10 years, it might have been possible to obtain a conclusive result. The Crown cleared the late McInnes of any involvement in the Bible John murders in July 1996.

"DNA at that time just wasn't quite there yet for that kind of material. It is now," she says. Cassidy cites a case she worked on in Ireland where, in 2007, five unidentified victims of the Stardust nightclub fire were finally successfully identified using DNA, some 26 years after their deaths.

"With the Bible John one, we were just a wee bit premature in rushing to do it at that time, but hindsight is a wonderful thing."

The cloying scent of death

"It is a smell you don't forget," she says. "Working in that environment for a few hours, you become accustomed to it and don't notice it clinging to you, but it clings to everything." According to Cassidy, the scent lingers on your clothes and hair – giving off an odour similar to rotting fish.

She recounts visiting a department store in Glasgow on her lunch break after a morning examining a badly decomposed body found in a wooded area. The deceased, she concluded, had likely died from alcohol or natural causes.

With the examination complete, she and a colleague popped into BHS. While he headed for the men's department, she visited the children's section.

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It was only after a customer in the queue loudly remarked on an awful smell that Cassidy realised the terrible odour was coming from her. She hotfooted it out of the store, bumping into her colleague at the door as they exclaimed in unison: "We smell".

Then there is the matter of eating after a post-mortem. "The smell clings to your hands," she says. "I remember being in Bosnia and we found a McDonald's in Sarajevo. We were eating hamburgers with a knife and fork because if you put your hand up to your mouth, you would have gagged."

Ireland and accidental fame

Cassidy swapped Glasgow for Dublin in 1998 to take up the role as Ireland's deputy state pathologist and found herself thrown into the public arena. "The Irish are obsessed with death," she says, wryly.

Her then-boss was Dr John Harbison, professor of forensic medicine and state pathologist in Ireland. Harbison, she says, "relished his fame" (once, while visiting Glasgow, he was flabbergasted by the anonymity of his Scottish counterparts).

When Harbison retired, Cassidy was appointed state pathologist in 2004, and, like her predecessor, her name became synonymous with murder and tragedy.

"I was a forensic pathologist in the Glasgow department for a long time and nobody really knew who we were," she says. "When I went over to Ireland, suddenly I was thrown into the limelight because I was a key figure in all these death investigations."

HeraldScotland: Dr Marie Cassidy, who was Ireland’s state pathologist for 14 years, arrives at Phoenix Park in Dublin in 2013. Picture: Brian Lawless/PA WireDr Marie Cassidy, who was Ireland’s state pathologist for 14 years, arrives at Phoenix Park in Dublin in 2013. Picture: Brian Lawless/PA Wire

People would say hello in the supermarket, surreptitiously checking out the contents of her trolley. The attention was well-meaning and generally pleasant, but Cassidy found it a double-edged sword.

"The problem was it made me become a bit reclusive," she says. "I thought: 'Well, I can't go out and get rip-roaring drunk' because people would be going, 'Is that not Marie Cassidy falling over in the street there?'

"Most of the neighbours didn't know who I was because I never came out of the house. Everybody knew my husband and my kids, but no one knew who this strange woman was. I was a bit like the mad auntie in the attic who was never seen in broad daylight.

"People would come up and say: 'You are doing a great job. It is wonderful what you are doing. Thanks very much, you did the post-mortem on our Mary…' while I would be going: 'Oh my God, do I really need to hear this in Marks & Spencer?'"

Taggart and adventures in telly

Forensic pathology isn't nearly as exciting or glamorous as TV makes it look, says Cassidy. Taggart, she reckons, is perhaps the most accurate in its portrayal, as the pathologist was confined to the mortuary and, once the post-mortem was over, that was the end of their involvement.

Cassidy worked as a consultant on the long-running STV crime drama series, although her notes to the special-effects department about authenticity were occasionally deemed too grisly for viewers and ended up on the cutting room floor.

"Forensic pathologists are passionate about what we do," she says. "Anybody who will listen our stories, we will talk to you. I would be the most boring contestant on Mastermind because I know nothing about anything other than death."

HeraldScotland: Dr Marie Cassidy worked as a consultant on Taggart starring Mark McManus. Picture: STVDr Marie Cassidy worked as a consultant on Taggart starring Mark McManus. Picture: STV

Cassidy lobbied unabashedly for Taggart to feature a female forensic pathologist – rather than the stereotypical middle-aged bearded male. She finally got her wish in 2001.

"I was dropping big hints: 'Hello, see this little person in front of you? I'm the one who does all this, not that big, bulky man with the beard you seem to have every week on the telly.'

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"The biggest compliment I got was people saying: 'You don't look anything like a forensic pathologist'. I'd go: 'Yes!' and 'What does a forensic pathologist look like?' People had this idea that you had to be some grumpy old man. That is just not reality.

"But that doesn't make good telly. It then became good telly once they had Silent Witness and CSI because they could make it glamorous. Suddenly forensics was becoming sexy and glamorous. I was like: 'Excuse me, I have been doing this for years …'"

Beyond The Tape: The Life and Many Deaths of a State Pathologist by Dr Marie Cassidy is published by Hachette Ireland, priced £15.99