Sandiford is an independent forensic science consultant, based in Auckland, whose job, she says, "is to make sense of science". In so doing, she can help bring about the acquittal of a wrongly accused person or help convict a wrongdoer.
For Sandiford, forensic science is science at its most basic. "It's been stripped down to the absolute bare bones, because that's what happens when you give evidence and that's how you should write a report - so that it's totally justifiable, easily explainable and can be understood by anyone."
Television is doubtless responsible for fostering in viewers' minds the belief forensic experts can trample all over a crime scene - usually of a murder - make a slick, quick examination, depart and invariably, at speed, arrive at a conclusion to help nail the criminal culprit. Not so.
Sandiford, who has plied her profession in Britain as well as in this country, says crime scenes should be recorded and documented (photographs, plans, maps, notes, diagrams, videos) before items are appropriately moved and removed.
"After that, a long chain of events occurs, every step of which should be recorded."
The author maintains that once a DNA result has been presented in court, "it is extremely hard to cast any measure of doubt on the result, even if it were fundamentally flawed in a given case; it's just a function of the automatic weight that triers of fact place on DNA findings."
Sandiford spreads her net wide as she discusses some of the thousands of criminal cases in which she has been involved.
If her aim is to keep simple the fascinating fare she serves up, she largely succeeds in that objective. Some of the material is best avoided by those with weak stomachs.
Her sense of humour shines through constantly. That is a trait doubtless almost a sine qua non for those in a calling often involved in the messy side of death.
The author was heavily involved in organising the contribution of expert defence witnesses from the United Kingdom in the retrial of David Bain, and she herself gave evidence about bloody sock prints at the scene of the family murders in Every St, Dunedin.
She describes the decision to become involved in the Bain case - which she terms "the Trial of the Century" - as "like walking into the eye of a hurricane." Expert Witness makes it plain she is a woman well able to withstand such buffetings.
•Clarke Isaacs is a former chief of staff of the Otago Daily Times.
