22 November 1983: 15-year-old Lynda Mann is found raped and strangled on a deserted footpath in the Leicestershire village of Narborough. Police find semen and a blood sample at the scene, but cannot identify a suspect. On 31 July 1986, a second 15-year-old girl, Dawn Ashworth, was found in a wooded area in a neighbouring village. She had been beaten, savagely raped and strangled. Richard Buckland, a local 17-year-old youth with learning difficulties admitted to the second murder under questioning, but denied killing Mann.

At the time Alex Jeffreys, a genetics professor at the University of Leicester, had discovered that patterns in some regions of a person’s DNA could be used to distinguish one individual from another. Jeffreys had used his DNA pattern recognition technique in paternity and immigration cases, but now the police asked for his help. When he analyzed samples from the murders, he found matching DNA from both crime scenes—but the recovered DNA didn’t match Buckland’s genetic code. Buckland was thus the first person to have his innocence proven by DNA analysis.

In an attempt to find the real culprit, the police obtained blood and saliva samples from more than 4,000 men in the Leicestershire area and had Jeffreys analyze the DNA. In due course, Colin Pitchfork was convicted via a DNA match and sentenced to life in prison.

That moment marked a watershed in both criminal investigation and in the crime fiction that follows in its wake. 

Let’s set the scene. By the 1980s crime fiction had long evolved from its ‘golden age’ where intuition, intellect and good old-fashioned doggedness were the primary means by which detectives tracked down evildoers and proved their nefarious crimes. Blood evidence, fingerprints, and various other scientific methods of crime scene analysis had moved the spotlight from the Sherlockian sleuth to the detective working in tandem with the forensic technicians. However maverick that detective might be, he (or she) was still required to kneel before the altar of crime scene analysis. 

But the fact remained that much of that evidence was open to either error or misinterpretation. This left plenty of wriggle room for crime fiction writers to create flawed case investigations (allowing for plot twists) and slippery villains able to laugh in the face of the scientific skullduggery that aimed to bring them low.

What DNA evidence did was to move the bar again. 

DNA profiling is as close to a magic bullet as law enforcement has yet come. Whilst every other type of evidence might be argued against, DNA matches are so statistically compelling that the possibility for error is all but dismissed. 

The effect on the criminal justice system has been seismic, revolutionising not only how investigations are conducted, but also starkly highlighting historical errors and police misconduct. The Innocence Project in the USA tells us that, since 1989, 367 DNA exonerations have taken place in America alone. During the same period thousands of prime suspects in other investigations were identified and pursued until DNA testing proved they were wrongly accused.

These are sobering statistics. For crime fiction writers – and readers – they provide compelling evidence of the potency of DNA profiling.In a real sense DNA has made crime fiction more science-based, behoving crime writers to understand the science behind modern evidence analysis. (Of course, sometimes fiction goes over the top leading to the godlike powers of law enforcement officials in TV programmes such as CSI.) Technological improvements in DNA analysis, resulting in the ability to analyse ever smaller quantities of DNA, have led to an ever-better ability to identify or convict criminals. 

Which, in turn, makes the task of a crime fiction writer more difficult. 

After all, how do we create suspense if there is a magic bullet out there ready to solve the crime within the first dozen pages of our novel? 

In a June 2019 Telegraph article Madeline Grant lamented that “since the advent of DNA testing, iPhones and CCTV” the fun has been taken out of detective fiction. She goes on to say that “Today, almost every crime drama seems to hinge on DNA evidence, rendering the deductive methods favoured by the likes of Sherlock Holmes, Hercule Poirot and Miss Marple obsolete.”

I couldn’t disagree more. Crime fiction is now the world’s bestselling genre. One reason for this is that crime writers have adapted to the new panacea. In some cases we fudge, ie. we invent clever criminals who watch cop shows and realise they must avoid leaving DNA at crime scenes. They shave off their body hair, wear gloves and hairnets, and bleach away incriminating DNA from corpses and crime scenes. (In reality criminals are rarely that clever!) 

More importantly, crime writers continue to stick to the formula that has underpinned the genre’s success. A great crime novel doesn’t need to fiddle about with pesky DNA. It needs only a compelling mystery, a likeable detective, and an immersive setting. 

I work at the UCL Jill Dando Institute of Crime Science where I have access to the latest forensic science research. Yet I do not feel the urge to shoehorn that research into my books. The bulk of my deductive method is done the old-fashioned way. Solving clues, interviewing witnesses, shoe-leather. 

DNA has changed crime fiction, of that there is no doubt. But beneath the science the fundamentals of a great story remain inviolable. Long may that remain the case.

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My latest novel is Midnight at Malabar House. Available from bookshops big and small and online, including here.