Few processes are more important to society than solving crimes, both to protect the public from criminals and to protect the innocent from unjust punishment. Very often, the strength of a prosecution rests on the ability of law enforcement personnel to connect the accused with the victim by matching physical evidence from the crime scene or victim with trace evidence found on or about the person accused of the crime. Forensic investigators consult a wide range of experts who analyze evidence collected at crime scenes and brought to the crime laboratory for examination. Forensic chemists perform specialized analyses to identify materials and learn the nature of such evidence. A highly trained forensic chemist can determine the composition and nature of materials and predict the source as well as matching sample against sample. Modern chemistry employs a wide range of analytical techniques along with traditional methods of analysis.
Physical evidence collected at crime scenes is sealed in special containers to prevent contamination and degradation and is catalogued carefully. A chain of custody is established and documented as the evidence is sent to a forensic laboratory. At the laboratory, the evidence is examined by personnel trained in one of several fields: Forensic serologists examine body fluids, forensic pathologists examine human remains, firearms technicians classify and test firearms and explosives, and forensic chemists determine the composition and identity of materials.