DNA Mixtures

[Ann Horsman]

This is a subject which I find to be a bit interesting and am looking for comments or knowlege from any of you who care to comment. It seems that some DNA analysis is subjective, mixtures present a problem where the analyst must make an opinion. One analyst told me they use a mathematical forumla to arrive at a conclusion rather than make the 'identification' based on observed characteristics from the testing.

[Pat A. Wertheim]

The topic of mixtures drew some criticism at the recent conference on the NAS Report at Arizona State University. I met some DNA experts there who are opposed to trying to separate mixtures to bolster a case against a suspect. I don't know enough about DNA to consider myself well informed, but apparently there are those who think mixtures can be misinterpreted and wrong conclusions can be drawn, whereas single source DNA is reliable.

[Gerald Clough]

I'm not about to try to sort all this out, but here are a couple of articles that go through the math. Makes it clear that there's likely no one in any courtroom, other than the expert, who has any chance of doing more than taking the expert's word for it:

http://www.fbi.gov/hq/lab/fsc/backissu/oct2000/fung.htm

http://dna-view.com/staincal.htm

Ya'll have fun with it.