In their book, Postmortem, Dr Steven A Koehler and Dr Cyril H Wecht describe forensic specialists who work with evidence from homicide investigations. Using cutting-edge technology and the latest scientific methods, these experts examine things such as insect activity and trace evidence to help determine the cause, manner and time of death.
Forensic Experts who Work with Homicide Cases
There are a number of forensic specialists who work in different fields of expertise. Their combined input can crack a case that would have gone unsolved in past decades:
· Forensic toxicologists examine the effects of chemicals on the body and analyse blood, urine, bile and eye fluid. They may perform simple drug tests or use sophisticated methods such as gas chromatography and mass spectrometry. They look for poisons, prescription and non-prescription drugs and alcohol · Forensic serologists work with genetic profiles gathered from fluids entered as evidence. These include blood, urine, saliva and semen. They look for genetic markers such as protein or enzyme compounds and determine blood types · Trace evidence examiners analyze trace substances including fibers, hairs, soil, glass, explosives and paint. Much of this evidence may be microscopic and is collected by lifting with tape, scraping, vacuuming, sweeping, combing and clipping. It is gathered from the body as well as the surrounding crime scene · Forensic entomologists are trained to recognize insects found in dead bodies. They are familiar with their life cycles and can estimate the time of death when it is unknown. This is particularly useful when a body is in an advanced stage of decomposition · Firearm examiners test firearms and compare bullets and cartridges. Gunshot residue is also tested for. A firearms examiner will examine a crime scene where bullets were fired and will establish a trajectory for the fatal shot as well as the distance the weapon was fired from
When are Forensic Experts Called in
There are a number of reasons for calling in a forensic specialist. Most of these concern verifying facts and producing evidence that an accused was at a crime scene. They can also help in determining the cause and manner of death. A forensic pathologist may refer a case to a forensic specialist if he is unsure as to what caused the victim’s demise. If a drug overdose or poisoning is suspected, the investigator will work with that information. Otherwise he will work methodically through the evidence available.
A homicide is normally handled by a number of forensic experts. They work with the evidence within their own areas of expertise and their combined results will normally result in the identification of the time, cause and manner of death.
Koehler, Dr Steven A and Dr Cyril H Wecht, Postmortem, Elwin St Limited, 2006.