Discussion
All DNA is is a means of identification. I say 'all' but identification is, of course, vital in any inquiry.
However, it is easy to overrate it. The best way of looking at it is as a fingerprint. It gives a name, a person, but that generally is all.
There is often confusion between the forensic evidence in general and DNA in particular.
However, it is easy to overrate it. The best way of looking at it is as a fingerprint. It gives a name, a person, but that generally is all.
There is often confusion between the forensic evidence in general and DNA in particular.
Derek Smith said:
All DNA is is a means of identification. I say 'all' but identification is, of course, vital in any inquiry.
It could be, but may not be. Various techniques are in use with differing degrees of ID power. Some are not particularly effective, some are very effective.Then there is the way evidence is presented, a matter covered in many online resources.
Consider
"If the suspect is innocent, there is a one in one million chance of obtaining this match."
which is often presented and interpreted as
"If this DNA matches, there is a one in one million chance the suspect is innocent."
Such a swapping of proposition and conclusion is a fallacy.
One in a million on its own sounds impressive. Yet if those seemingly overwhelming odds apply, they apply to 61 people in a country with a population of 61 million. Of those about 30 will be of the correct gender and (say) 10 not too young or too old to enact whatever crime is being tried. Do police ever bother to identify and rule out the other 9?
Clearly there may be other evidence which ties in one of the ten, and some test results can be even more stringent, but the implications of the techniques and the stats are often missed in my view, for the above reasons and others.
Completely agree with turbobloke on this matter, In particular his latest post and questioning whether the investigation rules out the other 9 people in a population of 61 million who may be a match. Now do the sums for a European population (>500million) and it gets even scarier.
Also it gets scarier still when people who should know better say things like "It gives you a name." ie assigning DNA evidence the property of the magical mystery tour silver bullet beloved by people who watch too much CSI / NCIS / L&O SVU and so on.
It's just one bit of the jigsaw, no more, and MUST be taken into due consideration with dabs, footprints, fibres, soil samples, evidence of location, and all the thousands of other bits of evidence, for AND against.
Unfortunately barrister theatricals could use the high probabilities to bamboozle an unscientifically inclined jury, in either direction depending which way the evidence fell.
Also it gets scarier still when people who should know better say things like "It gives you a name." ie assigning DNA evidence the property of the magical mystery tour silver bullet beloved by people who watch too much CSI / NCIS / L&O SVU and so on.
It's just one bit of the jigsaw, no more, and MUST be taken into due consideration with dabs, footprints, fibres, soil samples, evidence of location, and all the thousands of other bits of evidence, for AND against.
Unfortunately barrister theatricals could use the high probabilities to bamboozle an unscientifically inclined jury, in either direction depending which way the evidence fell.
MadMullah said:
the mystery still remains - who killed meredith.
Rudy Guede the one who is still serving 16 years (reduced from 30) for it and who had an appeal turned down I would imagine, unless the mystery "Italian" who appeared from nowhere and can't be traced did it.news said:
He has always denied murdering the British student, although he admits that he was in the house on the night of the murder. He claimed that he was flirting with Miss Kercher in her bedroom but had to run to the lavatory, having eaten a spicy kebab. While in the bathroom he heard screaming. When he rushed out, he said he was bowled over by a knife-wielding Italian man, who ran off into the night. Guede said he found Miss Kercher bleeding to death in her bedroom. In panic, he left the house and a few days later fled to Germany. He was eventually arrested, extradited back to Italy and put on trial. He was convicted on the basis of strong DNA evidence, including his bloody hand print on a pillow at the scene of the crime.
MadMullah said:
the mystery still remains - who killed meredith.
Rudy Guede or his unnamed accomplice perhaps?http://www.bbc.co.uk/news/uk-14978755
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