Truth Machine: The Contentious History of DNA Fingerprinting

The story of how genetic profiling revolutionised forensic science enthrals Charalambos P. Kyriacou

May 28, 2009

More than 20 years ago, I was chatting with my colleague Alec Jeffreys in the tea room of the University of Leicester's department of genetics, when I noticed a number of "suits" walk in, apparently looking for someone. They did not look like the usual visitors - laboratory-equipment salesmen - because their suits weren't smart enough. They looked more like characters from Life on Mars, the police series set in the 1970s.

Alec muttered something under his breath on the lines of "Oh dear", only that wasn't what he said, and he walked off with these fellows to his lab. Later that morning, I saw him shaking each of them by the hand in the foyer. They were detectives, and they left looking deflated.

Some time later, I asked him about this curious episode. He told me that he had been applying his "genetic fingerprinting" method to a local double-murder case (the so-called Narborough Village Murders), and had proved that a man who had confessed to these crimes was not the murderer. The cops had not got their man - no wonder they looked upset. However, Jeffreys' technique later confirmed the identity of the killer.

Jeffreys, now Sir Alec, developed the method in 1985, and a few years later improved it considerably with "genetic profiling", a related molecular bar-coding method by which almost everyone alive, and who has ever lived (except identical twins), can be differentiated. Being something of a witness to the evolution of these remarkable techniques, it was with some enthusiasm that I agreed to review The Truth Machine. I thought it would provide a good tabloid-style yarn for the public, but I could not have been more wrong. This book is anything but.

It is a serious discussion, laboriously researched, of the way genetic fingerprinting was applied, particularly in its early days, and how it became the gold standard for forensic science.

Other forms of evidence - eyewitness statements, for example, which are notoriously unreliable - paled into insignificance. The problem was that sloppy commercial forensic laboratories, and even sloppier interpretations of some of the data, were accepted by courtrooms uncritically, particularly early on. While DNA evidence exonerated many suspects, it was also used, sometimes incorrectly, to imprison others.

The authors dissect the sociology of DNA profiling, the techno-legal aspects, the probability arguments about how any two individuals might be related by chance, and the use of DNA databases, on which profiles of many members of the public are kept whether they have committed an offence or not.

They also show how clever lawyers were able to perform a valuable service by revealing the suboptimal procedures by which DNA evidence could be contaminated from the moment it was identified at a crime scene to its final destination in the lab, and how human error and misinterpretation could render the results meaningless or, worse, incorrect.

A particularly scurrilous case involved the Los Angeles Police Department during the O.J. Simpson trial. The lawyers representing Simpson destroyed the credibility of the LAPD's forensics lab yet, ironically, later initiated the Innocence Project. Here, DNA evidence that had been used to convict suspects, and had been maintained for years afterwards, was reanalysed with newer methods that were basically foolproof in the right hands. This has led on a few occasions to people being released after many years of incarceration, some of them on Death Row.

Sir Alec's discoveries here in Leicester have revolutionised forensic science. In the right context they provide an enormously powerful level of circumstantial evidence, which has been used to support arguments for and against the death penalty.

This book describes the first 20 years of their application and controversial early history. It starts a little slowly, and my eyes glazed over a little at some of the sociological ramblings, which, to my jaundiced eye, simply reflect the authors' intuitive grasp of the obvious. Once I got through the first couple of chapters, however, I could not put it down. This is a must-read for anyone interested in the history of science.

Truth Machine: The Contentious History of DNA Fingerprinting

By Michael Lynch, Simon A. Cole, Ruth McNally and Kathleen Jordan

University of Chicago Press 416pp, £26.00

ISBN 9780226498065

Published 20 January 2009

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