Forensic science is not infallible, as the Azaria Chamberlain case showed, but a new technique being researched jointly at the University of Technology, Sydney and the CSIRO looks likely to give investigators more certainty in the analysis of even tiny fragments of physical evidence.
The technique, using a microscope-focussed laser to vaporise minute parts of a sample, allows multiple testing without destroying the sample, even if it's a single fibre of fabric or a speck of paint.
The method could, for instance, be used to help determine the make of a car involved in a hit-and-run accident from traces of paint left on the clothes of a victim while allowing the traces of paint to be retained for further examination.
The research was begun last year by Steven Armitage, then a UTS honours student in forensic science, under the supervision of Dr Paul Greenwood (CSIRO) and Dr Claude Roux (UTS). The project is being continued by current honours students, with Mr Armitage acting as an adviser.
Mr Armitage, a university medal winner now studying for his PhD in forensic science, said the laser-microscope combination has been used by the CSIRO as an analytical tool in other branches of science, but has not previously been applied to forensic analysis.
Earlier techniques for the vaporisation and analysis of solid samples had been little used in forensic labs, Mr Armitage said, because relatively large samples were required and the material was destroyed in the process - an undesirable result in the eyes of the courts.
In his research Mr Armitage looked at three types of samples: paint, fibres and photocopier toners, with the best results, so far, being achieved with automotive paint. More work needs to be done on fibres and toners because some materials tend to be resistant to heating by the laser.
"Overcoming the problems with fibres will make this technique an extremely valuable tool, as fibres often are a principal type of evidence recovered after break-ins and in cases of sexual assault. You could have a single fibre and potentially get half-a-dozen analyses from it," Mr Armitage said.
