Solved: one cell is all it takes
The slightest human trace left at a crime scene may now lead to a conviction, following a new DNA test which relies on just one human cell. Even if he or she wears gloves, an offender's DNA 'fingerprint' could be all it takes to get caught.
Developed in the US and currently being trialed through the University of Queensland's Australian Genome Research Facility (AGRF), the test means that DNA evidence will now be available from a far wider range of samples.
AGRF senior scientist Dr Ian Findlay said the test could be applied to dandruff skin flakes, tongue cells on the backs of stamps, and smudges on steering wheels. Samples as old as 50 years could be analysed, he said.
"The test will also be able to differentiate between semen in a mixed sample, such as that taken after a gang rape. This is information not available using [current] forensic techniques," he said.
Once available to the courts, the test may result in many unsolved criminal cases being re-opened and the culprits brought to justice for crimes dating back many years.
Dr Findlay said the test uses polymerase chain reaction (PCR) and DNA sequencing techniques which can test even a tiny or contaminated sample.
"We've taken the old technique but refined it and optimised it so it is much more sensitive," he said. "Some of the things we've manipulated are the annealing (clumping) temperature, and the primer concentrations (primers amplify the DNA).
"At the moment the test is around 85 per cent reliable," he said.