Fingerprint research. Scientists working on a method of viewing fingerprints. Fingerprints are composed of amino acids, sebum, mineral salts and water. Here, the fingerprints are treated and fixed with indanedione and excited using a powerful green laser. The indanedione binds to the amino acids, which re-emit the laser's light by fluorescence. The fingerprints are therefore visible with the aid of special glasses or orange filters. Photographed at the Institut de recherche criminelle de la gendarmerie nationale (IRCGN), the forensic science department of the French National Gendarmerie, France.