On TV, DNA can be analyzed immediately…
Most molecular techniques take at least a full day or two. To perform the DNA tests, you must have cells with nuclei. So, you can extract DNA from hair, but you also need cells from the base of the hair.
On TV, people are always “losing” the criminal evidence...
In real life, if criminal evidence is collected, a “chain of custody” must be maintained. The evidence is collected, bagged, sealed without contamination, and then each person who has control of the specimen must sign for it.
In novels and TV, there are always “any number of” untraceable chemicals or poisons that did the poor guy in…
You first need to make a distinction between “untraceable” and “untraced.”
Most things are traceable, but an injection of potassium chloride would stop the heart. When death occurs for any reason, there is a natural rise in plasma potassium levels, which would render meaningless the measurement concentration in postmortem blood.
Potassium chloride is what is used in execution by lethal injection. Obviously, this method of homicide would require an intravenous injection. A good pathologist would be able to find the injection site, which would then raise suspicion.
So, there are things that are traceable, just not... “traced?”
Yes, there are other poisonings that are traceable, if they are specifically investigated. Routine investigations include detection of drug abuse (opiates, barbiturates, cocaine, amphetamines, etc.) Autopsies may not routinely include uncommon poisons such as heavy metals (salts of thallium), ricin (an extremely potent toxin derived from castor beans) and overdoses of injectible insulin.
On TV, the dental records are always mentioned. Are they that valuable?
The body, including bones burn but the anatomy of teeth is retained.
Forensic dentistry is important for the identification of the patient. Forensic dentists were key to identifying many of the victims during the 911 attack.
Also, teeth are as individual as fingerprints, as are the marks they leave. And saliva from the mouth and on the teeth may leave detectible DNA.
UPDATED: 10-30-2005
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Dr. Margaret Uthman is an associate professor of pathology and director of hematopathology at the UT Medical School.
See Dr. Uthman also at:
Dr. L. Maximilian Buja is a professor in pathology and vice president of Academic Affairs for UT Health Science Center at Houston.
See Dr. Buja also at:
Food Irradiation
and Safety
On August 22, 2008, the Food and Drug Administration (FDA) published a final rule that allows the use of irradiation to make fresh iceberg lettuce and fresh spinach safer and last longer without spoiling.
Irradiating fresh iceberg lettuce and spinach will help protect consumers from disease-causing bacteria such as Salmonella and Escherichia coli O157:H7 (E. coli). Illnesses from these bacteria range from uncomfortable symptoms to life-threatening health problems.
The foods affected by the final rule are
Irradiation (also sometimes termed "ionizing radiation") is a process of treating products with a measured dose of radiation. Food irradiation is not new. FDA has conducted irradiation safety evaluations for more than 40 years and has determined the process to be safe for use on a variety of foods.
After studying the safety of irradiating fresh iceberg lettuce and fresh spinach, FDA has determined that these greens, when irradiated under the conditions specified in the final rule, retain their nutrient value and are safe to eat.
FDA considers irradiation a complement to, not a replacement for, proper food-handling by producers, processors, and consumers. Irradiation is just another tool to reduce the levels of disease-causing microorganisms on fresh iceberg lettuce and fresh pinach.
Irradiation does not take the place of washing. FDA continues to recommend that consumers wash fresh and bagged produce before eating unless the packaging specifically states that the product has been pre-washed.
For more information, go to: http://www.fda.gov)
