Data Retention Regulations in the Lords

[Roland Perry]

In article 
<889e91640903301356v3b9402bcpb38a9e1c1af36e81@mail.gmail.com>, Alan 
Braggins <alan.braggins@gmail.com> writes
>>> (As for marking people who aren't twins but have duplicate results for
>>> the subset of DNA tested, that only helps if all of them have been
>>> tested and put in the database.)
>>
>> You'll only get potentially false positives if both are in the database.
>
>No, the really dangerous false positive is when the database says "this is
>the only match for the evidence", and someone not actually in the database
>actually did it.

I was under the impression that most of the time DNA evidence was used 
to prove which of a fairly small number of suspects had done the crime, 
rather than doing a country-wide trawl that turns up completely random 
people (random in the sense you never otherwise suspected them). I 
realise that the "CSI" model, and several "cold cases" we read about in 
the papers, give the impression that completely "random" people turn up 
as suspects, but once you've filtered out really trivial alibis like "I 
was only seven at the time" how often is someone prosecuted who lives 
300 miles away, and has absolutely no connection with the victim?
-- 
Roland Perry