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Forensics: Junk Science or Reliable Means of Conviction?

Posted September 10, 2008 12:00 AM by Sharkles

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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#1

Re: Forensics: Junk Science or Reliable Means of Conviction?

09/10/2008 2:58 AM

It's like any tool...it's only as good as the person using it.

In the UK there have been several old rape cases where DNA evidence has secured a conviction many years after the event.
However I don't believe we should all have our DNA on a data base as I fear it would be lost, stolen or sold.
The UK gov't has had a string of embasassing data losses this year.

Here's some I picked up in the street this morning 010111000101000111101001010011

Del

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#11
In reply to #1

Re: Forensics: Junk Science or Reliable Means of Conviction?

09/11/2008 11:15 AM

I concur with the cat on this one. If they only have a hammer, everything will look like a nail. But if they also have a screwdriver, and insufficient training to use it, it's still all gonna be nails.

OBTW, Del, that data you found in the street, Scotland Yard would like to have a word with you on that. Seems it's part of the digi code that operates the security gates at Buckingham Palace...

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#2

Re: Forensics: Junk Science or Reliable Means of Conviction?

09/10/2008 5:52 AM

My car was stolen a couple of years ago (not the first car I've had stolen), and written off. The forensics guys found a filter-tip from a cigarette in the car, from which they isolated DNA which matched a known car thief local to this area. They called me and asked me if I knew him (in case I'd had him in the car as a passenger). I'd never heard of him.

A few months later, I had an apologetic letter from the police saying that they'd taken the guy to court, but the case was thrown out because, despite the DNA evidence being accepted, the police fingerprint results had taken too long to process.

Now what's all that about? Presumably they'd been miss-filed, or lost in the post, or maybe they were on a laptop (lost by or stolen from the police)?

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#3
In reply to #2

Re: Forensics: Junk Science or Reliable Means of Conviction?

09/10/2008 6:00 AM

What a waste of tax payer's money..that would doubtless have been enough to buy a new car for you (and the car thief).

Del

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#4
In reply to #3

Re: Forensics: Junk Science or Reliable Means of Conviction?

09/10/2008 6:20 AM

That'd be funny if it wasn't so true & sad.

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#5

Re: Forensics: Junk Science or Reliable Means of Conviction?

09/10/2008 2:59 PM

I do think that DNA testing that doesn't rely on human perception is best. You gave the example of fingerprint testing, but it is my impression that blood testing/matching is much more conclusive and accurate. Fingerprinting much relies on people looking at the prints and such and we all know that people can (and are) be wrong a lot. "Close Enough" tends to work with some people and in the case of these 'experts', it seems like they were just being lazy and had the close enough attitude.

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#6

Re: Forensics: Junk Science or Reliable Means of Conviction?

09/10/2008 8:11 PM

The problem with DNA is it will tell you this DNA does not match and you know who didn't do it. When it does match it is saying that this person could be it. It is not 100% this is the one, but says of the very small group of this DNA match one of them is it. The problem is members of the exclusive group could be any where. Even in the jury box.

Brad

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#8
In reply to #6

Re: Forensics: Junk Science or Reliable Means of Conviction?

09/11/2008 2:50 AM

...Yeh...it was my long lost identical evil twin brother wot dun it guv'

Del

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#13
In reply to #8

Re: Forensics: Junk Science or Reliable Means of Conviction?

09/11/2008 1:36 PM

Don't laugh Carl is doing 300+ years and the Federal court even in a roundabout way admitted his (evil)twin brother driving an identical jeep probably did it, but Carl "was properly convicted and innocence is not a defense." (their words)

Just finished a 19 hour work day. Put a fork in me I'm done.

Brad

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#7

Re: Forensics: Junk Science or Reliable Means of Conviction?

09/11/2008 12:24 AM

On TV the CSI are also investigators. i never heard of that before.

On Tv a case is solved in a 45minutes(without commercials) while in real live it takes from a few weeks to years.

And these days your evidence is only as good as your lawyer (O.J anyone?)

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#9

Re: Forensics: Junk Science or Reliable Means of Conviction?

09/11/2008 7:58 AM

It should only be considered another tool.

But unfortunately because most people believe in what they see on TV shows. They think its a perfect way of identifying the criminal. But anything that can be interpreted by either a human or even a computer can give bad information. Remember even with a computer you put garbage in you get garbage out. And the person with the most convincing lawyer & so called experts in a court room. Wins

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#10

Re: Forensics: Junk Science or Reliable Means of Conviction?

09/11/2008 7:59 AM

I feel that it has merit, but people tend to think that it's the end-all-be-all and forget the rest of the evidence that may be out there. For example, there might be something less obvious but more concrete facing in either direction.

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#12

Re: Forensics: Junk Science or Reliable Means of Conviction?

09/11/2008 12:12 PM

Most of the technological stuff done on TV is junk, ask anyone who is involved with the forensic labs. Besides, as a juror on a recent trial, I saw up close that the protocols associated with collecting eveidence are rarely followed and if the sampling is poor the results will be meaningless.

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#14

Re: Forensics: Junk Science or Reliable Means of Conviction?

09/11/2008 3:16 PM

DNA profiling helped some 40 or 60 innocent "murderers" in the US waiting in their death cells if and when to be executed.

RHABE

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