Forensic testing isn't necessarily what you see on TV.
On the popular show CSI, staff from a Las Vegas forensic lab solve multiple crimes within the show's hour-long format, presenting forensic testing as quick producers of irrefutable court evidence. But unlike the glitzy, made-for-television lab scenario, real-life forensic laboratories' analyses of evidence are much slower.
For example, when pop star Michael Jackson died in 2009, results of Forensic Toxicology tests on his brain tissue took almost a month. That's not unusual. Tests can take weeks or even months to complete because of technical requirements of different forensic tests, limited availability or integrity of some samples, complexity of testing for illicit and therapeutic drugs and other toxic chemical agents, and the extensive record keeping necessary for legal proceedings. Sometimes tests are beyond a laboratory's scope of expertise, so it must send specimens to more specialized laboratories.
Forensic testing is the gathering of data for analysis and for use in legal proceedings, depending on the laws of particular jurisdictions. "The legal aspect of forensic testing separates it from clinical testing," explains Steven Wong, PhD, director of Milwaukee County forensic toxicology laboratory in Wisconsin. This legal aspect requires a certain way of handling samples, use of specific testing methods as required by law, and following a "chain of custody."
The chain of custody requires documentation of every person who has handled the sample and everywhere it has been. If the chain of custody procedure is handled correctly, forensic laboratory evidence can be admitted in court with the assurance that the item was collected from the stated location and/or person in question without compromising the evidence.
Laboratory staff who handle and process such specimens typically receive special training that is pertinent to both laboratory science and the legal demands of forensics. Forensic laboratory technicians often have clinical training, while forensic pathologistshave completed medical school, residency programs, and specific forensic training. Forensic pathologists conduct postmortem examinations on body tissues, blood, and/or other bodily fluids collected during an autopsy or from the crime scene and interpret the findings to determine the cause, the manner, and the time of death, and in some instances, to establish the identity of the deceased.
A forensic pathologist may work in one of two death investigation systems, a medical examiner system, or a coroner system. A medical examiner is an appointed official, usually a forensic pathologist, who is responsible for the investigation of suspicious or untimely deaths for a particular jurisdiction. In contrast, a coroner is an elected official and may be a forensic pathologist but also may be any type of physician or even a lay person. Those cases that may be of a legal concern could be re-directed to a forensic pathologist to perform the actual examination.
Unlike clinical laboratories that are certified under specific standards of the federal Clinical Laboratory Improvements Act (CLIA), forensic laboratories prove their competence to other accrediting organizations such as the College of American Pathologists (CAP), American Board of Forensic Toxicology, the National Forensic Science Technology Center (NSFTC), and American Society of Crime Laboratory Directors/Laboratory Accreditation Board.
While TV has brought much attention to the laboratory profession, it often does not reflect the reality of what takes place. Because of the complexities of forensic testing, few if any laboratories can do all the types of testing that may be required. Not all laboratories provide the comprehensive testing menu that may be needed when looking for specific genetic markers. Even certain blood tests may have to be referred to a "specialty" or reference laboratory. The collection of samples, their preparation for testing, performing the tests, and evaluating all the results takes time and money to complete. While technology has greatly advanced forensic science over the past decade, certain limitations still remain.