On 30/04/2013 12:44, Big Les Wade wrote:
However, such inferences (using what's called low copy number analysis)
are still very controversial, and are at the very least a great deal
more indirect than those from simple full-length DNA matching. Which
itself isn't perfect either, despite what they tell you.

I think the DNA case may be worse than your well described example.

With the splodges on the wall there are all sorts of non-destructive
analyses that can be carried out - photographs in UV light, oblique
lighting, image enhancement - none of which are destructive so you can
repeat them at will.

In the case of a tiny splodge on a knife you have to wipe it off in
order to test it, and once you've done your polymerase reactions you
don't have it any more.

Andy