New 'Magic' Pen to Help Catch Criminals

The pen, created by Dr. John Bond from the University of Leicester's Department of Criminology, provides forensic experts, police and criminal investigators with an easy-to-use method of determining whether a receipt, such as those from petrol stations, supermarkets and ATMs, is printed on thermal paper.

The pen works by initiating a chemical reaction on the paper that changes its colour if it is thermal.

Once identified as thermal paper, a specially designed light source is used to identify fingerprints on thermal paper that can be used to catch criminals by the paperwork they have been touching.

"The 'magic' marker pen works by impregnating the paper with a small amount of a chemical that I discovered will react with the dye, changing its colour. This chemical is mixed with others in the marker to provide a viscous liquid, ideally suited for application with a marker-type pen," Bond said.

"The idea is that a small corner of the receipt could be marked with the pen and if it changes colour it is thermal paper. Touching a small corner of the receipt will minimise the potential destruction of any fingerprints on the paper, helping to retain forensic evidence. The pen-like shape of the device will be handy to have in the pocket for technicians to apply as and when it is needed," said Bond.

The conventional method of treating non-thermal paper turns thermal paper black, obliterating any fingerprints in the process, which cannot be undone.

The pen allows for paper to be quickly identified, which will be useful in criminal investigations when extracting fingerprints from a variety of paper documents is necessary.

"Enabling the police service to make use of advances in technology is very important in helping to solve and reduce crime," Bond added.