Research into new fingerprinting technology that could reveal a suspect’s diet, drug habits and even their ethnicity has received Home Office funding.
The test method, which uses a laser to identify molecules in the sweat that fingerprints are formed from, could determine what substances a suspect has touched or ingested and what time they were in a location in order to help link them to a crime.
The Home Office Centre for Applied Science and Technology has co-funded a £80,000 PhD studentship at Sheffield Hallam University to develop the technology, following the success of researchers there in creating a new way to capture the prints.
The group has already successfully developed a method for testing substances a suspect has touched, referred to as exogenous substances, even when the fingerprint has been distorted or is incomplete.
This could be particularly useful in tying suspects to cases of sexual assault where the perpetrator has used a condom and has lubricant in their fingerprint.
Now they hope to use a similar method for detecting endogenous substances, which appear in sweat after a suspect has ingested a food or drug.
‘Anything that can be secreted in sweat can be picked up in fingerprints because they are a simple deposit of sweat,’ said Dr Simona Francese from the university’s Biomedical Research Centre.
‘It would be reasonable to think that you might pick up dietary habits of people. The profile of a vegetarian could be very different from a meat-eater. You could pick up whether a person was a smoker, a passive smoker or not.’
There is additional evidence to suggest it may be possible to determine a person’s gender or ethnicity from the chemical make-up of sweat, she added.
The researchers have also shown, based on feasibilty tests, that it might be possible to pinpoint the age of a fingerprint and therefore the time at which the suspect was at the scene of the crime. They are now planning to develop a tool to reproduce these tests more easily.
To analyse the fingerprints and determine what chemicals they contain, the researchers use a lab-based technique called Matrix Assisted Laser Desorption Ionisation Mass Spectrometry Imaging.
This involves adding an organic acid to the sweat particles to create crystals. These are then vaporised by a laser, freeing up the different ions in the substance and allowing them to be analysed with electromagnetic fields (a process known as mass spectrometry).
This method provides a breakdown of all the molecules detected at specific coordinates and repeating it across the fingerprint allows the researchers to build up an image of what substances it contains using specialised software.
‘The technique is so powerful because while other techniques used in forensics with fingermarks at the moment targets a specific class of biomolecules we can detect many kinds in one analysis,’ said Francese.
The researchers caught the eye of the Home Office after they developed a type of dust that can capture fingerprints from a much wider range of surfaces than existing methods, up to 10 days after the marks were made.
The government now wants the team to further test the technology, including its use testing for illegal substances such as explosives, and ensure it is compatible with other techniques used by police forensic teams.