For the last twenty years or so we’ve gradually come to depend more and more on forensics to solve crime, with some films, books and tv series (cough CSI cough) making it look even more reliable than it perhaps actually is. However, this recent article in The New Scientist is a real eye-opener.
Written by one of the experts in the infamous Amanda Knox case, it particularly highlights the problems when dealing with infinitesimally small traces of DNA (as was apparently the case with one of the mainstays of the prosecution case, the supposed murder weapon). Here DNA expert Greg Hampikan reveals that the ‘miniscule’ trace of Knox’s DNA on the knife would not have been enough to count as evidence in many courts around the world – and that the Italian authorities never managed to replicate their initial results.
In spite of this (and a number of other odd quirks of evidence, or the lack of it) Knox was convicted of murder, then freed on appeal, then re-convicted, then finally cleared by the supreme court in Italy. But overall, the case illustrates that the sort of glossy forensic certainties favoured by CSI and similar shows is a very long way from reality.