The traditional use for fingerprints is to match them up with the fingers of people who have touched items in a crime scene. They can be used to prove someone was at the scene. Advances in technology allow the CSI team to do more with a fingerprint.
Mass spectrometry can be used against traces found within a fingerprint. These traces can show that the person who left the print is a smoker, used drugs or had handled explosives recently. How is this done?
When a finger touches a surface, sweat and other substances called “sebum” leave behind a print that can’t be seen by the naked eye. It is easy to make a fingerprint visible, by dusting the surface with powder or spraying with a superglue or re-agents. If a person has taken drugs, traces are released in sweat. A team working at the University of East Anglia, Norwich UK, has devised a method by which magnetic particles (with antibodies added to them) attach themselves to certain drug or nicotine metabolic substances. Secondly, they apply a fluorescent marker via another antibody, which binds to the first antibody and indicates the presence of a corresponding drug as they glow under a fluorescent light. By using this method, researchers were able to detect several different narcotics simultaneously in a single fingerprint.
Mass spectrometric techniques can be used to identify the components of sebum and their decomposition products in fingerprints. Mass spectrometry uses the light spectrum of elements to identify them when a light is shone through them or bounced off them. One approach is as follows. Solvent droplets are sprayed onto the surface to form a film which dissolves materials out of the fingerprint. Additional solvent drops impact the film and release the dissolved chemicals from the surface so that they can be analyzed by mass spectrometry. The chemicals in the fingerprint are examined by a computer. Traces of drugs and explosives can be identified from their light spectrum.
Infrared spectroscopy has been used to separate overlapping fingerprints from two individuals by means of their different sebum contents to produce two separate images. It is also possible to detect traces of explosive. Infrared spectroscopy can be used to identify medicines like aspirin and paracetamol, as well as caffeine and starch in fingerprints.
The aim of this research is to develop a portable, cost-effective, rapid, small system that can detect both fingerprints and the chemical components within them. This would be useful for CSI experts, but also for doping tests and diagnostics.
Burglars and murderers are advised to wear gloves at all times in future. If you have already left a fingerprint in the wrong place, your drug habits may be found out in the future.