State Pathologist warns that even forensic science has its limits

Forensic pathology offers a "guide" rather than a set of "hard and fast" rules about the circumstances of a death, State Pathologist Prof Marie Cassidy has said.

Addressing the National Prosecutors’ Conference at the weekend, Prof Cassidy said it was a misconception that autopsies could conclusively resolve all unanswered questions about homicides. She cited time of death as an example, saying the standard scientific method of estimating this – through body temperature – had been discredited in a recent case in the UK. “I think that is unfortunate, because I don’t think it’s the science that is particularly wrong. I think it was the pathologist who was wrong, because he gave the wrong impression to the court that this was a very particular type of science which could give you a particular answer,” she said. “It’s not.”

She quoted British forensic pathologist Bernard Knight, who described the exercise of estimating time of death as follows: " 'When were they last known to be alive? When were they found dead? They died some time between the two.'

“That’s as good as it gets, even today,” she added.

She said many of the cases she worked on were relatively straightforward. The cases that caused most “angst” were those in which injuries were relatively minor but death had occurred as a result of the interaction between the trauma and the presence of natural disease, drugs or alcohol.

“A lot of things are not hard and fast. The big buzzword in medicine nowadays is ‘evidence-based medicine’. That’s simpler when you’re looking at how well cancers react to certain treatments . . . But how do you go about doing it with our type of work, where the end result is always death?”