On Thu, 15 May 2008 08:31:51 +0100, Les Invalides
wrote:
>Yes, and of course it depends what it matches. If it fully matches a
>semen sample found on a murdered 5-year-old's dress, that's one thing.
>If it partially matches a saliva sample found on a cigarette end near
>the scene of a burglary, that's quite different.
Don't be so certain that a match of a semen sample on a dress
constitutes good proof of itself.
There has been at least one case that I know of when unbeknown to the
investigators, the evidential sample did not contain any viable DNA at
all. It was sent away for DNA analysis along with a sample from all
the people who had known contact with the victim. A miniscule amount
of contamination from a suspect's DNA sample to the evidential semen
sample occured, which after LCN amplification ended up giving a
completely false match between the semen DNA and the suspect's DNA.
Also, it is by no means impossible for a criminal to plan ahead by
planting semen from a used condom at the crime scene.
--
Cynic
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