DNA and the Crime Writer

I’ve written this piece on my fascination with DNA, I hope you find it interesting
– Lynda x

The many differing forensic sciences and their application to criminal investigations have always played a major part in my crime stories, in both my literary and television endeavours. When I first started writing crime drama in the 80s, it would be fair to say that forensically most crimes were solved through fingerprints, the comparison of fibres on clothing, and the ABO grouping of blood stains; the latter being particularly unreliable. The identification of murder victims was done, where possible, by fingerprints, through dental records or by visual recognition.

In 1986 the world of forensic science and crime investigation was revolutionised thanks to an earlier ground breaking discovery by Professor Sir Alec Jeffreys. He identified DNA differences in the human body that makes each one of us unique, which could be recovered from hair, saliva, body tissue and blood amongst other things. The implications of this discovery became far-reaching and were first used in 1986 to link two murders, securing the conviction of the perpetrator, Colin Pitchfork. Interestingly the suspect’s DNA recovered from the victims also exonerated an innocent man, as it has done many times since the Pitchfork case.

‘What a fantastic breakthrough’, I thought at the time, but not so good for the crime fiction writer, who inevitably needed to string out an investigation and often used good old fashion policing methods to solve the case. It was only three years earlier that I had written Widows, a TV series where a badly burned, and mutilated male body is wrongly identified by his wife. His recognisable traits being his size and the engraved watch he wore. Since the discovery of DNA fingerprinting, I realised I could no longer get away with that sort of story line… Or could I?

All too often in the flashy labs of crime dramas, no one argues about whether the DNA is a match, the results are seen as conclusive, end of story. However, in the real world, it’s not so straightforward and there may be innocent and viable reasons as to why a person’s DNA was recovered at a crime scene. Indeed you and I could shake hands, your DNA transfers to mine, I pick up a knife and I have deposited your DNA on it. Not that I’m suggesting I would then stab someone with said knife!

Other factors to consider are human error, after all none of us can categorically say we don’t make mistakes. Human error can occur, for example, where a DNA stain at a crime scene becomes inadvertently contaminated, which has been known to happen. Errors also occur when the DNA retrieved at a scene, or on a victim, is ‘mixed’, meaning it is from more than one person and the experts must painstakingly try to separate out the different sources.

For me as a writer, the burning question is not whether it is the suspect’s DNA, but more how did it come to be at the crime scene. Was it an innocent transference, or something more sinister? In the Anna Travis novel Blood Line, I used an unusual approach to this question, but you’ll have to read the book to know the answer.

Murder Mile by lynda La Plante. Out in Hardback on 23rd August.

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