On May 14, 8:06=A0am, Dead Paul wrote:
> I'm unsure if the British system is equally flawed but it's an angle
> which I had not previously considered.
> This account is relating what's currently happening in the USA.
>
> <<
> Like fingerprints, DNA are very powerful and scientifically sound
> evidence, when used to connect a known suspect to evidence found at the
> scene of the crime. Jurors are easily persuaded to accept the DNA link for=
> someone who had already been suspected of a crime scene when told the odds=
> against a false identification are 1 in millions or billions.
On its own the DNA match evidence is not all that exciting, but it
does suggest a list of people you might want to interview.
Fingerprints have also been known to have their problems most high
profile one recently being:
http://news.bbc.co.uk/1/hi/scotland/634282.stm
>
> But DNA is far less certain when you compare one sample against all of the=
> profiles in the database typically known as one-to-many. In that case the
> chances that a match between a DNA sample -- especially an incomplete one
> -- and a person in a DNA database could nab an innocent person has
> different math. Very different math.
But with any luck the innocent person will be geographically in the
clear. There is still a risk from false positives in a large database
though, but it still cuts down the number of suspects to a managable
number.
There could be other DNA ambiguity problems with identical twins and
chimeras.
> Exactly, you need other corroborating evidence before DNA evidence is even=
> worth a spit. Without that other evidence your DNA match is virtually
> certain to latch on to an innocent person as well as the guilty party
> (assuming he is in the database).
It is in the sense that it suggests people who should be interviewed
as a part of the enquiry.
AFAIK they are only using it on serious unsolved crimes in the UK and
I would rather have them interview a few innocent folk because of
false positives than leave murderers and rapists out on the street to
offend again.
Regards,
Martin Brown |