Forensics: What Bugs, Burns, Prints, DNA and More Tell Us About Crime

by Val McDermid

A defence barrister once put the framing idea to Val Tomlinson in court, claiming that his client’s LCN DNA had been planted at the scene by an anonymous other. To prove it, he asked Val a hypothetical question: ‘If you were going to set somebody up for this how would you go about doing it?’ ‘I don’t think I could,’ said Val. In Val’s experience most set-ups fall down on basic points. ‘Children go over the top when they are trying to cover up for their mistakes. And you tend to find that people who frame others distribute too much blood in the wrong way, or a whole bucketful of glass instead of the two little pieces which is what you would expect to persist on a piece of clothing recovered a week after a crime.’ Like any powerful tool, DNA can be misused. But, as always, the analysis of evidence is not simply about the collection of data – whose DNA is or isn’t there – but also about the interpretative skills of the scientists who deal with it. This is what should – and mostly does – protect the innocent.