Collecting forensic evidence Forensics officer (gloved hand) collecting forensic samples from the fingernails of a suspect. Dirt, soil and other debris collected under fingernails provide important evidence in criminal investigations. The samples are analysed using microscopes, x-ray diffraction and DNA sequencing to provide detailed information on their composition. This information can be used as evidence to connect the suspect in relation to the crime. Photographed at the Macaulay Institute, Aberdeen, UK.