The scientific examination of evidence in criminal cases is called forensics, or forensic science. Forensic scientists use the same instruments and techniques used by scientists doing other types of research, including microscopes, computers, gas chromatographs and lasers. As science has advanced, so has the ability to gather evidence and solve crimes. At crime scenes, portable lasers provide special lighting. Imaging technology lets a police officer instantly send a photo or fingerprint image to a central data bank for identification. Computers can enhance pictures taken by a camera at a bank. New chemicals allow the visualization of otherwise unseen fingerprints. Lasers can vaporize tiny portions of a paint specimen to determine the exact paint used on a car in a hit-and- run case. A single cell can provide DNA that molecular biology techniques can match with a suspect. Thousands of scientists and detectives have contributed to forensic science. Foremost among them have been:
Great care must be taken in collecting, labeling and preserving any evidence connected with a crime. The police must be able to prove that the evidence was always in their possession from the time it was taken at the crime scene until the time it appears in court. Anyone who has access to the material must be documented. They must prove that the object shown in court is the same object that was tested in the laboratory. If these cannot be proven, the judge may rule that the chain of custody has been broken and the object may not be admitted into evidence. As soon as an object is found it is placed in a container,sealed and labeled. The place where the object was found and when it was found is noted and the officer initials the label. When the evidence goes to the police station or forensic lab it is placed in a locked evidence room where only a few people have access. An exact record is maintained of everyone who has the evidence in his or her possession. For example, at Hickory Police Department, only two people have keys to the evidence room. The room is in a vault shielded by cement and has no windows or other access.