Drowning in the DNA Database

Well, well, well:

The number of crimes solved thanks to the DNA database is actually falling despite the ever-growing number of people it contains.

Figures given to Parliament show that even though 7 per cent of the UK population are now on the DNA database it helped solve only 0.36 per cent of crimes, down from 0.37 per cent last year. In the same period over half a million people have been added to the database.

In fact there has been no big improvement in convictions since 2000/2001 when the database contained just 1.2 million people but was useful in 0.29 per cent of recorded crimes.

In other words, the database contained most of the useful DNA eight years ago: since then, it's been one long fishing expedition, adding more DNA for the sake of it - just in case. As the figures prove, the vast majority of that DNA is of innocent people who are are apparently unlikely ever to commit a crime. The only possible reason for retaining it is because of the insane authoritarian urges of the present government.

And what on earth does this quote from the Home Office mean?

The benefits of the NDNAD lie not only in detecting the guilty but in eliminating the innocent from inquiries

The only way the innocent could be eliminated is if their DNA had a flag "innocent" against it, which would make their presence in the database ridiculous. Assuming such a flag does not exist, how on earth does having some people's DNA - past offenders and innocent bystanders - help to eliminate the innocent?