Disclosure has been a constant refrain from us for many years.  Two recent cases raise new disclosure issues. 

Labs frequently check that DNA samples have not been contaminated by police or lab staff.  If the samples are contaminated then they should be discarded, not introduced as evidence.

In a case involving the finding of DNA on a weapon, the lab discovered the DNA from one of the police staff on a key sample.  This is troublesome in itself, but even more troubling are the facts that this was not mentioned in the scientist’s statement or provided to us in the lab casefile.

Just a one-off?

Apparently not.  In court the very next day we discover that the police had contaminated yet another sample in a separate case.  Yet again, this was not mentioned in any scientific statement or in the lab casefile.

So what’s the problem?  Many.

First, the scientific process includes checks that the samples have not been contaminated.  What’s the point of that if you don’t acknowledge that they have been contaminated?

Second, if they have been contaminated by an identified person then there is no reason that they could not have been contaminated by someone else who may have transferred not only their own DNA but the DNA of the person of interest.

As a consequence of these ‘unfortunate’ discoveries, we have now amended our standard disclosure request to include confirmation from the lab that they have not identified sources of contamination.

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