Wed, 22 Nov 2006

The DNA good practice manual

The Association of Chief of Police Officers (ACPO) published today the DNA Good Practice Manual, Second Edition 2005. The following table from this document reveals that success rate in retrieving DNA from various samples is different in reality from what movies would make one believe:

Evidence typesSuccess rates
Semen 90%
Blood 87%
Chewing gum 78%
Cigarette butts 75%
Fingernail clippings 69%
Comb/Razor 53%
Hair with roots 50%
Saliva 40%
Hair without visible roots15%
Cigarette lighter10%
Watch strap8%

Unfortunately this document includes other surprises such as the mention that DNA profiles in the NDNAD are not destroyed even when an profiled individual dies. I wrote more about this and some other aspects directly affecting me in a new entry on the Innocent in London page.

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