• WANTED: Happy members who like to discuss audio and other topics related to our interest. Desire to learn and share knowledge of science required as is 20 years of participation in forums (not all true). Come here to have fun, be ready to be teased and not take online life too seriously. We now measure and review equipment for free! Click here for details.

How DNA sends innocent people to prison

Cosmik

Major Contributor
Joined
Apr 24, 2016
Messages
3,075
Likes
1,980
Location
UK
#1
https://www.theguardian.com/science...wed-techniques-send-innocent-people-to-prison

What makes me a little bit angry about this is the idea that "As forensic technology gets ever more sophisticated, experts are only just realising how difficult interpreting the evidence can be." Did they not consider that possibility before?

Like Michael Gove, I am not an expert in anything, but I would have thought that being asked to believe that people inadvertently leave traces of themselves wherever they go and whatever they do, yet at the same time to believe that the presence of DNA is strong evidence that they were at a particular crime scene at a particular time doesn't add up. If we are leaving DNA everywhere, then it could happen at any time, and could quite obviously be transferred from environment to another person and back into the environment multiple times. As the article says, DNA can even be transferred on coins.

And in the article it describes how DNA analysis is now in the hands of private companies who use 'proprietary' statistical techniques to establish guess whether there is a match from incomplete, or mixed, fragments, but that their methods are a 'black box' - and anyway, even if people have access to the source code, no one knows whether the fundamental logic behind it is valid.

And this doesn't even address the issue of possible deliberate contamination of a crime scene with someone else's DNA.

Clearly DNA should not be regarded as the primary evidence in a case.
 

iridium

Addicted to Fun and Learning
Joined
Feb 28, 2016
Messages
525
Likes
108
#3
Good Read: "The Crossing" by Michael Connelly.

iridium.
 

Wayne

Active Member
Forum Donor
Joined
May 26, 2017
Messages
172
Likes
45
Location
Los Angeles, CA
#4
What makes me a little bit angry about this is the idea that "As forensic technology gets ever more sophisticated, experts are only just realising how difficult interpreting the evidence can be." Did they not consider that possibility before?
A couple of thoughts (truths) about evidence.

1. Evidence, like most statements, must be taken in context. The presence of evidence such of DNA, fingerprints, etc. by itself is good (maybe even great) evidence that a person was present at a certain place or handled a specific object. But, it is not absolute evidence. Very few things in life are absolute (err.... save taxes and death). The more evidence supporting the source of DNA and fingerprints, (ie: DNA on a vaginal swab or fingerprints in a victim's blood) and/or circumstantial evidence related to the incident, the stronger the overall evidence the person was present.

2. New evidence is sometimes used in court (or by investigators) before it has been subjected to rigorous testing.

Clearly DNA should not be regarded as the primary evidence in a case.
This is true, especially when dealing with mixtures and touch DNA,

Edit: related article https://www.forensicmag.com/news/20...6122433&et_rid=%%subscriberid%%&type=headline
 
Last edited:
Top Bottom