If you are looking for Glamour, Gadgets and Grissom you won't find them here. Forget what you think you know about 'Forensics', these are the tales of one man and his brush. Of course these views do not represent the views of any Police Force or indeed reflect any Force Policies ya da ya.

Friday, 21 December 2007

Low Copy Number

A judge has ordered an immediate review of LCN DNA following the Omagh Bomb verdict. For those unaware of what LCN (Low Copy Number) DNA is, it is basically a super-sensitive technique that can extract DNA from areas touched or handled by someone, that sample is then amplified, a bit like photocopy enlarging, until a usable profile is obtained. This profile is nowhere near as accurate as a full profile obtained from something like Saliva or Blood which would have a discriminating factor of 1 in a Billion of being anyone else, instead a LCN profile can give you a much more ambiguous result giving you a huge list of names of who it could be instead of who it most likely is. This list of names could be whittled down by Detectives based on geography, offender description or maybe flag up the name of a known suspect.

I would liken this type of evidence to that of a fairly tenuous eye witness account, it gives you an idea of who it might be but not enough to be used as evidence. In general Policing terms it's better known as intelligence and not something that you would base your prosecution on. I'm not sure in what form this LCN evidence was used in the Omagh case but to base your whole case around it would be foolish and at most circumstantial.

It would be a shame however if the FSS withdrew this technique in future as it is a very useful intelligence tool. I have had some great results in previous jobs where an offender wasn't known and just being given a name has opened up so many other lines of enquiry and other evidence gathered has come back to these people. On the plus side at least some of the clueless Police Officers will stop asking for us to swab every door handle in sight on the off chance that the force may fork out a couple of grand to process them.

1 comment:

Anonymous said...

This is a completely incorrect description of LCN DNA analysis. It is quite posible to obtain a full profile with the 1 in 1 billion statistic.