Non-destructive fingerprint collection techniques

Traditional methods for collecting fingerprints often use powder, liquid or steam, and they can destroy fingerprints for later analysis. A technique using X-rays will fix that.

This technique aims to detect salt in human sweat - which creates the contours of fingerprints. If the fingerprint retains enough salt, it will recognize it without interfering with the sample.

Scientists from Los Alamos National Laboratory used a thin X-ray beam to illuminate fingerprints - a technique called X-ray fluorescence (MXRF). Elements such as sodium, potassium, chlorine are present in human sweat that absorbs X-rays and emits light, or "fluorescence," in low-frequency form.

The technique could also identify these substances when fingers covered by cosmetics, soil, saliva or sunscreen - pollutants that lose the accuracy of traditional crime investigation methods.

The method can collect fingerprints on different materials, such as paper, wood, leather, plastic and even on human skin. It is also useful in identifying children's fingerprints, which have little oil on the skin. In addition, experts can get more information from fingerprints. For example, the last piece of food of murder suspects.

"This is a new tool for forensic investigators, which allows them to detect fingerprints by non-destructive methods, which traditionally can be ignored," said Chris Worley, team leader. said.

The MXRF method takes 2 to 5 years to apply to practice. Its drawback is that sometimes the amount of detectable material is too small. X-rays do not recognize lighter (and more common) elements such as carbon, nitrogen and oxygen.