From the distribution of cocaine in the fingerprint (a) measured by the new method, a computer can generate a classic fingerprint (b). It agrees remarkably well with the computer variant (d), which was calculated on the basis of a classical ink fingerprint (c). Image: Science / AAAS
Read aloud From the fingerprint, criminologists will be able to recognize in the future with the help of a new technology what the associated hand has recently touched. Researchers at Purdue University in West Lafayette, USA, have developed an appropriate methodology to accurately analyze the chemical composition of a fingerprint. At the heart of this process is a so-called mass spectrometer, which can detect even the smallest amounts of chemicals. The researchers want to search for traces of drugs and explosives. To make the fingerprints readable to the mass spectrometer, the researchers spray the impression with water in the presence of an electric field to ionize the molecules on the fingerprint. The material thus obtained is then sucked off and analyzed. Thanks to the precise resolution of the device, the researchers can distinguish between skin-specific and exogenous substances.

Thus, the scientists succeeded in their experiments to detect even the smallest amounts of cocaine and explosives in fingerprints. Five millionths of a gram of a substance was enough to leave behind a recognizable chemical trace in the fingerprint. Even several superimposed fingerprints could distinguish the researchers so certainly.

With the new method, however, not only chemical investigations can be carried out. The graphic structure of a fingerprint can also be analyzed very precisely by the researchers. With the help of imaging techniques, details are displayed in a resolution of around 150 thousandths of a millimeter. A fingerprint obtained in this way can then be examined using conventional software, for example to determine the identity of a person.

Demian Ifa (Purdue University in West Lafayette) et al .: Science, Vol. 321, p. 805 ddp / Markus Zen's ad


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