Data Retention Regulations in the Lords

[Pete Mitchell]

John Brazier wrote  on 31-03-09 06:01:
> Roland Stated:
> 
>> 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, 

That's what it was developed for, and how it was sold to Parliament.

>> rather than doing a country-wide trawl that turns up completely random 
>> people (random in the sense you never otherwise suspected them). 

That's what's often done now. For example, Operation Advance, a national 
review of undetected serious crimes set up by the Home Office Police 
Standards Unit in 2004.

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?
> 
> Well, there's this case:
> <http://books.google.co.uk/books?id=4NMgAMsdpNEC&pg=PA43&lpg=PA43&dq=DNA+Ray
> mond+parkinson+burglar&source=bl&ots=m5E5tMN9VU&sig=3cDvLxA4PZgiK6da8OMDk7wC
> rXQ&hl=en&ei=IaDRSZCKOebKjAfj15X3Bg&sa=X&oi=book_result&resnum=8&ct=result>
> (Judicial Error and Forensic Science, Huff & Killias, p43)
> 
> There's also:
> http://www.forensic-evidence.com/site/EVID/DNA_Watters.html
> although one could argue that the person in question had been arrested for a
> similar offence, and he was in the same city!
> 
> That's two UK cases in two years.

There have been many more. I recall one from Advance where a guy was 
convicted of rape based on the facts that (i) he turned up in the NDNAD 
trawl (ii) he lived in South East England (iii) he was a labourer. The 
crime had been committed 16 years earlier, giving him virtually no 
chance of proving an alibi.  The prosecution naturally said "the 
likelihood of the DNA sample belonging to someone else was one in a 
billion", showing just how phenomenally, catastrophically ignorant these 
people are about the rules of valid inference. And that's if we assume 
they are honest.

-- 
Pete Mitchell