A new method of recovering fingerprints shows great potential in capturing criminals. Felons often wipe bullet casing to remove their sweaty prints, and until now it was a fairly successful way of not getting caught.
The new technique makes use of the salt left behind even after the sweat was removed. As a corrosive substance, salt microscopically etches the fingerprint into the metal shells. A fine powder is then dusted on the casing and the metal is charged electrically causing the dust to adhere to the corroded areas, exposing the hidden loops and whorls. This process only works if the perpetrator has enough salt in their system, not everyone does.