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Forensics on television is amazing. Investigators are immediately on the scene collecting evidence, and then bringing it back to headquarters and running tests. In these TV dramas, there is usually evidence from which DNA can be extracted. Almost always, this evidence leads to the capture and conviction of the criminal. The good guys win and the bad guys go to jail.
Unfortunately, life does not imitate art. DNA fingerprinting is a technique that can be used for anything from determining paternity to condemning criminals. Fingerprints are the reflection of each person's individual DNA, which can be found in blood, hair, tissue, etc. Forensic fingerprinting relies on the exploitation of Variable Number Tandem Repeats (VNTRs), or short nucleotide sequence repetitions. With DNA testing, a suspect's culpability is based on the similarity between his or her DNA profile and evidence obtained at the crime scene.
Reliability Called Into Question
Forensic fingerprinting is often revered as a useful and generally reliable test, but some claim that it is not scientifically validated. When fingerprints are collected from a crime-scene, they are often smudged, distorted, or gathered in segments rather than in strands. This makes it hard to prove that the fingerprint is unique.
The problem is that large-scale research to confirm the uniqueness of fingerprinting tests has not been conducted. Results are unverified by statistical fingerprint variations, or by a consistent error rate. Because human beings administer and interpret these tests, human error could produce inaccurate results.
Studies Show Inaccuracies
In 1995, the International Association of Identification approved a proficiency test involving a fake crime scene. Of the 156 examiners who took the test, one out of five made at least one "false-positive" identification – thus connecting the crime to the wrong person.
Another study was conducted by the University of Southampton in the United Kingdom. This study suggested that subjective bias could also influence forensic evidence. Five fingerprint examiners were asked to determine whether latent prints – impressions left at crime-scenes and visualized through dusting techniques – matched those from a suspect. The examiners were told that the prints had been matched incorrectly by FBI fingerprint examiners the year before. In reality, each examiner was given a different set of prints – ones they'd presented in court previously as definite matches.
One examiner correctly identified an assigned pair as matches. The four others wound-up changing their identification from the original decision that they'd presented in court five years earlier. In other words, 80% of the examiners essentially changed their testimony.
Unfair Representation?
Forensic fingerprinting can also be controversial in its presentation. If forensic analysis is misinterpreted or exaggerated by lawyers, then it could mislead jurors. Instances of PhotoShop usage or staged DNA evidence have also come into play.
Additionally, forensic DNA testing is not cheap. If defendants are unable to hire their own DNA experts, they may not be able to defend themselves against DNA evidence.
It seems like the "jury is out" on this issue. Still, I'd like to thank U V and Milo for bringing it to my attention. Admittedly, I'm not an expert on DNA testing or fingerprinting. But I've learned from writing about this topic that it's an extremely interesting and complex controversy.
What do you think?
- Are DNA fingerprints reliable evidence?
- Is forensics a "junk science" or does it have merit?
Resources:
https://www.sciencemag.org/cgi/content/summary/302/5651/1625
https://www.thenakedscientists.com/HTML/articles/article/dalyacolumn8.htm/
https://www.truthinjustice.org/fingerprints.htm
https://science.jrank.org/pages/2129/DNA-Fingerprinting-Genetic-fingerprinting-forensic-tool.html
https://technology.newscientist.com/channel/tech/forensic-science/dn8011-how-far-should-fingerprints-be-trusted.html
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Re: Forensics: Junk Science or Reliable Means of Conviction?
