GETTING away with murder used to be a piece of cake. Back when fatalities didn't need to be registered, death certificates were often signed by doctors who hadn't bothered looking at the deceased and perhaps simply took a neighbour's word that Mr McNab from upstairs had died in his sleep or finally succumbed to the drink. Poisonings were explained away as the result of natural causes and even where a crime was suspected, bodies were sometimes buried quickly to avoid the cost of a formal investigation.

This disquieting insight into 1840s Scotland comes courtesy of husband-and-wife crime-writing duo Marisa Haetzman and Chris Brookmyre, who researched the period extensively for their Edinburgh-set historical novel The Way Of All Flesh, which is published under the pen name Ambrose Parry.

“Toxicology was in its infancy,” says Haetzman, a consultant anaesthetist with a PhD in the history of medical innovation. Already, however, chemistry was “a blossoming science” and in the ensuing decades, advances in photographic evidence, fingerprinting and body fluid analysis would make it increasingly difficult for criminals to avoid leaving tell-tale traces.

Then came DNA profiling, which allowed killers to be definitively linked to their victims – even in cases that had been cold for decades. “Take the World's End murders,” says novelist and screenwriter Lin Anderson, referring to the 1977 killings of two young Edinburgh women which were finally solved in 2014, when DNA evidence secured the conviction of Angus Sinclair.

Something similar happened with Bible John, says Liam McIlvanney, whose novel, The Quaker, was inspired by childhood memories of the hunt for the notorious serial killer of late 1960s Glasgow. “There was a semen stain on a dress,” he adds, “and they dug up a suspect's body in 1996 … But they didn't get a DNA match.”

All this talk of poisonings, digging up bodies and semen stains, makes me glad this conversation is taking place in the otherwise deserted basement of Glasgow's Blackfriars pub, where the authors have gathered to collaborate on the somewhat dodgy-sounding mission of producing a blueprint for committing the perfect (fictional) crime.

With the Bloody Scotland crime-writing festival only days away, this seemed an opportune time to ask these participating authors to share some of the knowledge they've gleaned from their research into the grisly business of murder.

They are, after all, experts on the trail of clues that lead to killers being convicted. By extension, Scottish Life reckoned, they must also know the pitfalls to avoid in order to escape detection.

So here they are: huddled around a table in a windowless, strip-lighted basement, revealing the secrets of their craft. And here is their guide to getting away with murder …

The killer

Rule number one: don't look like a murderer. “Making yourself look unlikely as a suspect involves trying to make it impossible for people to believe it would be you,” says Brookmyre. A look of respectability or fragility might help. You could, as McIlvanney suggests, take a leaf from WH Auden's famous essay on crime fiction, and cultivate the high-minded attitude of a university professor who seems so cerebral that no-one would suspect him of murderous passions like lust, avarice and envy.

Secondly, surround yourself with people who look more guilty than you. “One of the key things in the Bible John case was the proliferation of suspects,” says McIlvanney. “That's essentially how he got away with it. He was known to be male, aged 25-40, with short fair hair.” Aside from a few details about his clothing, favourite cigarettes and fondness for quoting from scripture, little else was known about him, and although Glaswegians to this day swear they know the identity of the real Bible John, the mystery has never been solved. “Creating a wide field of suspects for the police to get lost in” is therefore key, according to McIlvanney.

The weapon

Lin Anderson, creator of the famous fictional forensic scientist Rhona MacLeod, spends a lot of time talking to real-life forensic experts and she's heard from a reliable source that “one of the easiest way to get away with killing someone is to push them off a hill or a cliff. It's very, very difficult to prove”.

“Especially if it's just a small shove,” agrees Haetzman.

“Or if they slip a bit and you help them,” adds Anderson.

As someone who “hates violence”, Haetzman suggests poison is the obvious method “if you wanted to get rid of someone but weren't prepared to do something deeply unpleasant like shooting or stabbing them”.

You have to choose your toxin, of course. Arsenic – the Victorian killer's substance of choice – is useless in the 21st century because, being metallic, it doesn't degrade and is easily detectable.

For Haetzman, poison's primary advantage is that it offers a “degree of separation” between killer and victim. “It distances you from the act,” agrees Brookmyre. “Even pushing someone over a cliff, there comes a moment when you know you can't escape the physicality of the act. With poison, you can almost fool yourself. It's almost as if you put the means of death into the victim's hands: just give them the poison and go away. That's what makes it such a powerful weapon: you don't need physical strength or even the mental fortitude to confront the reality of the violence you are inflicting on someone.”

Killing another human being is not, after all, a natural thing to do and Brookmyre cites research conducted after the Second World War which showed that most soldiers couldn't actually bring themselves to pull the trigger. Given that most people aren't capable of taking someone's life, what interests him as a writer is – so what makes them able to do it?

“Exactly,” says Anderson. “Psychology plays a big role in all these books – the why is as important as the how.”

The victim

Murder may be their bread and butter, but when talk turns to the most likely target of our perfect crime, these authors' revulsion for the real thing becomes starkly apparent.

“The perfect victim is someone no-one will miss,” says Brookmyre simply, echoing something author Andrew O'Hagan once said about the young women killed by Fred and Rosemary West, some of whom were never reported missing. "They were killable," a policeman told O'Hagan as he researched his book, The Missing. "And the Wests knew how to pick them off.”

The crime scene

The clever killer chooses a location witnesses are ashamed to admit having been in. As McIlvanney reminds us, two of Bible's John's crimes happened on Thursdays, when the Barrowland Ballroom's over-25s dances took place. “It was the classic night when the wedding ring would come off and go into the pocket,” he says. “So if you are looking for witnesses who were at the Barrowland on a Thursday evening, people are not going to come forward.”

As Brookmyre points out, people are also notoriously reticent where the victims are sex workers, since admitting to having seen something suspicious may identify them as having used their services. “Those women's lack of respectability in society's eyes also means they have often been seen as low priority,” adds Brookmyre, though it's to be hoped those perceptions are changing.

A time to kill

Winter, when daylight hours are short, is the most suitable season. “Darkness allows for the covering up off all sorts of deeds, makes witness accounts less reliable and helps with disposing of the body,” explains Brookmyre.

Choosing a time when discovery might be delayed is another tactic, and Haetzman mentions the real life case of a GP who injected his wife with a huge dose of insulin on New Year's Eve – presumably hoping holiday-related delays in discovering the body would mean the insulin had disappeared from the body. He was caught – partly because his internet search history showed he'd researched the amount of insulin needed for a lethal dose.

Disposing of the evidence

Without a body, says Lin Anderson, it's very difficult to prove that a crime has been committed. But in a world monitored by CCTV and smartphone tracking, how do you get rid of the remains without arousing suspicion? Anderson suggests heading into the wilderness. “In Scotland, if you go north and slightly west, you just need to go in between the mountains to find pockets where you are off-grid. How would a body ever be found among all those acres of Sitka spruce? Or under the vast expanse of snow in the Cairngorms, where when people disappear, they're often not found until the snow melts in spring.”

“In New Zealand, where I live,” says McIlvanney, “you don't have to travel far to find places where human foot has never trod. So if you helicoptered into Fiordland on the South Island, tramped on into the wilderness and disposed of a body, no-one's going to stumble on it.”

“But I guess it's the transporting that leaves a trail,” says Haetzman. “How do you actually drag a body up a mountain?”

What about firing it into orbit? Chris Brookmyre, whose latest solo novel, Places In The Darkness, is set on a space station, shakes his head, pointing out that a body lost amid an otherwise empty expanse of space would actually be easily traceable using radar. Then he drops a hint about his current novel-in-progress, and recommends the ocean as the ideal repository. It never reveals footprints, there's no shallow grave and the creatures of the deep are notoriously good at consuming the evidence.

Too much information? “Obviously in this article we don't want to tell people how to commit the perfect murder,” says Anderson, in a disclaimer that may not stand up in court. Don't these writers ever worry about giving readers the wrong kind of ideas? No, says Anderson, who, as a policeman's daughter, insists that real life criminality is far more depraved than anything they could dream up.

All the same, as we climb upstairs and step into the noonday sunshine, it occurs to me that if any foul deeds are committed hereabouts this afternoon, the Blackfriars Four had better hope that those basement walls do not have ears …

Lin Anderson, Chris Brookmyre, Marisa Haetzman and Liam McIlvanney are all appearing at Bloody Scotland: Scotland's International Crime Writing Festival, which takes place in Stirling September 21-23

Sins Of The Dead by Lin Anderson is published by Macmillan, £14.99

Places In The Darkness by Chris Brookmyre is published by Orbit, £8.99

The Quaker by Liam McIlvanney is published by HarperCollins, £12.99

The Way Of All Flesh by Ambrose Parry (Marisa Haetzman and Chris Brookmyre) is published by Canongate, £14.99


Val McDermid

Plot: The best, most secure way to commit a murder and get away with it is to make it look like an accident.

Disposing of the evidence: Getting rid of the body is difficult unless you keep pigs, which will eat pretty much anything. I heard a case a few years ago about a pig farmer who collapsed and died, and all they found of him was his belt buckle.

Timing: Researching a book about real women private eyes in America a few years ago, I spoke to an insurance investigator who said if you want to get away with murder, do it on a Saturday night in Southern California, because the police are so busy, anything they can write off as an accident or suicide, they will. Not that I would recommend it.

Does she fear inspiring copycat crimes? People don't sit down and read my books and think: “Oh jings, that's a good way to get rid of the wife.” That's not how murders happen. Most murders aren't planned, they're committed on the spur of the moment through drink and drugs.

I once wrote a book about a small plane being blown up mid-air, which I researched with Prof Niamh Nic Daeid at the University of Dundee before settling on a recipe for the bomb. When I wrote the book I made a deliberate mistake – obviously, because I didn't want people going up and blowing people up. In the intervening years I've had several men – and it's always been men – saying to me: “You know you made a mistake in that book …?”

On the whole, the way we write about crime in our books is far more ingenious than the real crime that happens in the real world. And the real world contains much more horror and hideousness than any of us ever put into our books.

Broken Ground by Val McDermid is published by Little, Brown, £18.99

Doug Johnstone

The best way to get away with murder, says the Edinburgh-based author, is “to commit a crime that nobody cares about solving. The secret is probably to kill someone that doesn't have any family, and that you have not connection to”.

Johnstone isn't strictly a crime novelist and his new novel, Fault Lines, takes place in a re-imagined Edinburgh in which a tectonic fault opens up to produce volcanic island in the Firth of Forth, where his protagonist goes to meet her secret lover. When she actually encounters his body, she walks away … and becomes a suspect in his murder. “I'm interested in the split-second decisions people make when they are under a lot of pressure, which then come back to bite them,” says Johnstone. “We all like to think we'd be heroes: that if the Titanic was sinking, we'd be the ones helping others into the lifeboats. But in reality, most of us wouldn't be all that heroic under incredible stress and pressure.

“Rather than one-dimensional serial killers, it's more interesting to write about ordinary people thrown into morally grey areas and seeing how they cope. So what I'm asking readers isn't whodunnit but – what would I do in that situation?”

Fault Lines by Doug Johnstone is published by Orenda Books, £8.99

Charles Cumming

Shortlisted for the McIlvanney Prize for his current novel The Man Between, this Ayr-born novelist's territory is espionage rather than crime.

“If I was writing a crime novel I could speak to detectives or lawyers, but it's quite difficult to find spies in the Yellow Pages – or ones who are prepared to talk to you. A lot of the business of spying is about winning people's trust so you can get information from them or build a relationship with them in terms of surveillance.”

So what makes the perfect spy? “Spies are usually highly intelligent, well-educated people with good memories. A certain ruthlessness is useful, as is a degree of courage. Living a double life is hard, however – not being able to tell your friends or even your partner where you're going, who you've been talking to, what you've been doing. At a personal level, living a deceitful life will eventually take its toll. To go through the whole of your professional life in duplicity is a great burden and very few people – Kim Philby being one of them – are able to carry it off; usually at the price of several divorces or alcoholism or the betrayal of friends and colleagues.”

The Man Between by Charles Cumming is published by HarperCollins, £14.99


Follow The Dead by Lin Anderson, Places In The Darkness by Chris Brookmyre, The Quaker by Liam McIlvanney and The Man Between by Charles Cumming make up the shortlist for this year's McIlvanney Prize For Crime Fiction. The winner will be announced at Bloody Scotland on September 21