5 Forensic Science Myths


Mystery: why is this trainer so clean? (photo: West Midlands Police, creative commons license)

CSI’s wise-cracking investigators, expensive cars, and sexy co-workers with great hair? High on the drama scale, low on reality. Crime and mystery writers striving for drama and accuracy have to get past such exaggerated expectations. Deborah Cole, a forensic scientist with the New Jersey State Police, spoke to a recent meeting of the Liberty States Fiction Writers Group about forensic science myths.

The first is how television has primed people to believe that forensic science is infallible. The reality is that it cannot always provide definitive answers. Nor is it true that scientists never make mistakes or mess up the chain of custody. Sometimes “a good defense attorney can find holes,” she said. (Interestingly, criminals have become aware of the power of forensics and have learned from tv how to cover their tracks more effectively.)

Response is not as fast as people expect. Some states have only one crime laboratory, and crime labs are often small and outfitted with, well, not-the-latest equipment. As a result, they may have a backlog of testing to do, which adds to the time needed to complete tests (or whether they are ever completed at all, with unexamined rape test kits a prime example). Some tests themselves take a long time to produce results. Tests for different toxic substances must be conducted individually, and all this may take a month or more to complete.

Forensic scientists do not interrogate suspects and witnesses, regardless of what tv suggests. Not their skill set. And they certainly don’t make arrests. They may be called to a high-profile crime scene, but they aren’t there first (unlike in the UK’s Midsomer Murders tv series where the ME and crime scene team is always working away—with findings!—by the time the investigating detectives arrive). When they do visit a scene, they collect evidence to bring to the lab for analysis by someone else.

One scientist cannot handle an entire case. Forensic scientists are specialized (in the lab, their focus may be toxicology, chemical analysis, ballistics, and so on), which means that the evidence from a single case may be tested by a number of different scientists. The New Jersey State Police lab employs 130 scientists in different disciplines, and they are involved in some 35,000 cases a year.

Another reason one person can’t do it all relates to the Locard exchange principle: “whenever two objects come in contact with each other, there is always an exchange of material.” The practical application of this principle is that material from the clothing, floor, furniture, car, or other environs of the crime, which is gathered from the scene, from the victim, and from the suspected perpetrator (if there is one) must all be processed in different rooms and even by different people, in order to avoid cross-contamination.

Finally, Cole said (and she laughed when she said this), tv gives the impression that every day is exciting!

Further Information:

♦Useful for writers: http://www.forensicsciencesimplified.org/onducting Forensic ♦Research: A Tutorial for Mystery Writers: http://www.writing-world.com/mystery/forensics.shtml
♦Forensic workshops, including “TV v. Reality”: http://www.crimemuseum.org/forensic-workshops
♦Forensics: What Bugs, Burns, Prints, DNA, and More Tell Us about Crime, by Val McDermid (2015)


2 thoughts on “5 Forensic Science Myths

  1. Fundamentally, life is never as exciting as the movies/tv indicate. Dramatic licenses is usually one to enhance the truth. to the point of non-recognition.

    But we wouldn’t watch and be entertained if drama were real to life. As Hesse wrote in The Journey to the East, “… [we] … lose [ourselves] in the soundless deserts of mapped out reality, …”

    • Definitely. The problem arises when people start to believe that tv/movies ARE real life! That DNA evidence is always available, etc., etc.

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