In recent years we have come to think of DNA testing as a ‘gold standard’ that can convict or exonerate. But forensics experts urge caution. William Thompson declares:
‘DNA tests are not now and have never been infallible.  Errors in DNA testing occur regularly. DNA evidence has caused false incriminations and false convictions, and will continue to do so.’

Nathan Robinson explains that, as with all forensics, DNA testing arose from the need to prosecute criminals; as a result science’s core principles of neutrality and doubt are compromised. He adds,
‘Analysts themselves can be fallible and inept; the risk of corruption and incompetence is no less pronounced simply because the biology has been peer-reviewed.’

And the authors of The Truth Machine* remind us,
‘Police and prosecutorial motives and practices … come into play when DNA evidence is treated less as an abstract source of “truth” than as material that is collected, handled, labeled, and possibly planted.’
They conclude:
‘“DNA” does not transcend mundane, organizational practices or the possibilities that reside in stories of a crime’.

We should bear those caveats in mind when considering Jeffrey Wogenstahl’s case. DNA testing on a tiny speck of blood from the inside of a rear car door handle was linked to the victim in his case. Yet this minute blood speck is inconsistent with the prosecution’s theory of the case (that Jeff murdered a child, Amber Garrett, in his car).

Alongside the DNA evidence we should consider what The Truth Machine* authors call ‘the possibilities that reside in stories of [the] crime’.  And those ‘stories’ are: prosecutorial misconduct, unconvincing evidence, and the withholding of significant exculpatory evidence. They point not to Jeff’s guilt, but to his innocence.

*Michael Lynch, Simon A. Cole, Ruth McNally and Kathleen Jordan   The Truth Machine: the Contentious History of DNA Fingerprinting (The University of Chicago Press, 2008), p. 345

**Michael Lynch, Simon A. Cole, Ruth McNally and Kathleen Jordan   The Truth Machine: the Contentious History of DNA Fingerprinting (The University of Chicago Press, 2008), p. 346