Police cars race through the streets, the wail of their sirens alerting listeners that something has gone wrong. A call has just been received: a man was seen plummeting to the ground from his 10th storey balcony. Was it suicide or was John Doe murdered? Forensic specialists can help find the answer to this question.
Forensics is a very broad field, and many traditional disciplines—including medicine, dentistry, psychiatry, anthropology, and psychology—have forensic specialties. Let's imagine that a team of forensic workers is called in to investigate John Doe's death. The role they play in determining who or what killed John Doe will depend on the area of forensics they work in.
The first forensic workers to arrive after a crime is committed are the crime scene investigators (CSIs) who examine the crime scene and collect as much information as they can. CSIs may sketch and photograph the area—in John Doe's case this included where he landed, as well as his apartment and balcony. The area may be swept for fingerprints, footprints, hairs, and blood. Their job is very important because CSIs must make sure that the evidence isn't destroyed and follow strict rules of removal and packaging. If the evidence is improperly gathered, it cannot be used in a court of law because of concerns about contamination. After collecting the evidence, CSIs take it to a crime lab.
Once the evidence gets to the crime lab, forensics technicians and specialists perform tests on it to find out if anyone other than John Doe was at the scene. If so, the tests can reveal that person's identity. In the case of John Doe, a forensics technician found tissue samples under his fingernails which supported the idea that John Doe was murdered, or at least had a physical fight with someone the night he died. Crime lab specialists tend to specialize in one type of evidence, such as documents, hairs and fibres, fingerprints, chemistry, DNA, or photography.
Another type of forensic worker who would be involved in cases like John Doe's is a forensic pathologist. A pathologist performs an autopsy (also called a post-mortem) to figure out when and how the person died. This may include looking at various samples such as tissue, blood, or urine under a microscope, in addition to an overall examination. The forensic pathologist called in to investigate John Doe discovered that he didn't die from the fall but rather a blow to the head prior to the fall, which ruled out suicide.
Forensic psychologists look at the behaviour of the alleged criminal. So, if the police had tracked down the person believed to have killed John Doe, a psychologist may then be asked to interview the suspect and determine whether or not he or she was mentally fit to stand trial. Forensic psychologists may also counsel people in trouble with the law, or act as consultants on human behaviour. Some are involved in research that examines issues such as eye witness reliability, re-offending rates of released criminals, and profiles of various types of offenders.