CRIMINALS who try to fox detectives by altering their distinctive tattoos could soon be outwitted by new technology, thanks to University of Derby experts.

An infrared digital camera could become a crucial tool in trying to identify suspects by their tattoos.

Forensic scientists and detectives traditionally focus on the distinguishing features of a suspect when looking to track down offenders and those sporting tattoos can help provide a crucial lead in an investigation.

But criminals can currently stay one step ahead by hiding their tattoo through alterations.

Now, university forensic science experts are exploring how using an infrared digital camera can determine if a tattoo is an original, or if it is a second tattoo covering the old one.

A traditional colour camera only picks up what is on the surface of the skin but, using a digital camera sensitive to infrared, researchers can see if there are hidden layers or changes to the original tattoo deeper in the skin.

In a recent experiment, the technique was able to determine that a butterfly had been used to cover up an image of an imp tattooed onto a student's back.

David Bryson, university senior lecturer in applied photography and forensic science, also specialises in forensic imaging and he has been working on the project, with forensic science degree students.

Mr Bryson said: "Identifying individuals using tattoos has been an established part of forensic science practice for some time but there can be cover-ups of tattoos with lasers, more tattoos or surgery.

"It is now possible to take a control photo and a separate one with an infrared filter to determine if the tattoo is, indeed, the original or is a cover-up, or altered tattoo on the surface.

"Digital photography means that moments after the images have been taken, they can be viewed on a laptop or computer screen – making this interesting approach now more feasible for use in everyday forensic work, compared to more traditional processes."

Further research is now being undertaken at the university's laboratories at Kedleston Road, Derby.

Once the research has gone further, Mr Bryson will be looking at trialling digital infrared photography in police forces as a tool to look at tattoos.

Other forensic work trialled using photographic techniques include analysing lipstick left on coffee cups and ear prints found on glass.